diff --git a/src/library.js b/src/library.js
index 09fe8de2b225a..87deaa1299b7a 100644
--- a/src/library.js
+++ b/src/library.js
@@ -2362,12 +2362,8 @@ addToLibrary({
   },
 
   $HandleAllocator: class {
-    constructor() {
-      // TODO(https://github.com/emscripten-core/emscripten/issues/21414):
-      // Use inline field declarations.
-      this.allocated = [undefined];
-      this.freelist = [];
-    }
+    allocated = [undefined];
+    freelist = [];
     get(id) {
 #if ASSERTIONS
       assert(this.allocated[id] !== undefined, `invalid handle: ${id}`);
diff --git a/src/library_fs.js b/src/library_fs.js
index b5cf19e5d3a03..116fd76f73b59 100644
--- a/src/library_fs.js
+++ b/src/library_fs.js
@@ -74,6 +74,7 @@ FS.staticInit();
 #else
     ErrnoError: class {
 #endif
+      name = 'ErrnoError';
       // We set the `name` property to be able to identify `FS.ErrnoError`
       // - the `name` is a standard ECMA-262 property of error objects. Kind of good to have it anyway.
       // - when using PROXYFS, an error can come from an underlying FS
@@ -84,9 +85,6 @@ FS.staticInit();
 #if ASSERTIONS
         super(runtimeInitialized ? strError(errno) : '');
 #endif
-        // TODO(sbc): Use the inline member declaration syntax once we
-        // support it in acorn and closure.
-        this.name = 'ErrnoError';
         this.errno = errno;
 #if ASSERTIONS
         for (var key in ERRNO_CODES) {
@@ -100,16 +98,11 @@ FS.staticInit();
     },
 
     FSStream: class {
-      constructor() {
-        // TODO(https://github.com/emscripten-core/emscripten/issues/21414):
-        // Use inline field declarations.
-        this.shared = {};
+      shared = {};
 #if USE_CLOSURE_COMPILER
-        // Closure compiler requires us to declare all properties in the
-        // constructor.
-        this.node = null;
+      // Closure compiler requires us to declare all properties ahead of time
+      node = null;
 #endif
-      }
       get object() {
         return this.node;
       }
@@ -139,21 +132,21 @@ FS.staticInit();
       }
     },
     FSNode: class {
+      node_ops = {};
+      stream_ops = {};
+      readMode = {{{ cDefs.S_IRUGO }}} | {{{ cDefs.S_IXUGO }}};
+      writeMode = {{{ cDefs.S_IWUGO }}};
+      mounted = null;
       constructor(parent, name, mode, rdev) {
         if (!parent) {
           parent = this;  // root node sets parent to itself
         }
         this.parent = parent;
         this.mount = parent.mount;
-        this.mounted = null;
         this.id = FS.nextInode++;
         this.name = name;
         this.mode = mode;
-        this.node_ops = {};
-        this.stream_ops = {};
         this.rdev = rdev;
-        this.readMode = {{{ cDefs.S_IRUGO }}} | {{{ cDefs.S_IXUGO }}};
-        this.writeMode = {{{ cDefs.S_IWUGO }}};
       }
       get read() {
         return (this.mode & this.readMode) === this.readMode;
@@ -1667,17 +1660,14 @@ FS.staticInit();
       // Lazy chunked Uint8Array (implements get and length from Uint8Array).
       // Actual getting is abstracted away for eventual reuse.
       class LazyUint8Array {
-        constructor() {
-          this.lengthKnown = false;
-          this.chunks = []; // Loaded chunks. Index is the chunk number
+        lengthKnown = false;
+        chunks = []; // Loaded chunks. Index is the chunk number
 #if USE_CLOSURE_COMPILER
-          // Closure compiler requires us to declare all properties in the
-          // constructor.
-          this.getter = undefined;
-          this._length = 0;
-          this._chunkSize = 0;
+        // Closure compiler requires us to declare all properties ahead of time.
+        getter = undefined;
+        _length = 0;
+        _chunkSize = 0;
 #endif
-        }
         get(idx) {
           if (idx > this.length-1 || idx < 0) {
             return undefined;
diff --git a/src/library_wasi.js b/src/library_wasi.js
index ff78134aad0b7..f75458f20ce3c 100644
--- a/src/library_wasi.js
+++ b/src/library_wasi.js
@@ -6,11 +6,12 @@
 
 var WasiLibrary = {
 #if !MINIMAL_RUNTIME
-  $ExitStatus__docs: '/** @constructor */',
-  $ExitStatus: function(status) {
-    this.name = 'ExitStatus';
-    this.message = `Program terminated with exit(${status})`;
-    this.status = status;
+  $ExitStatus: class {
+    name = 'ExitStatus';
+    constructor(status) {
+      this.message = `Program terminated with exit(${status})`;
+      this.status = status;
+    }
   },
   proc_exit__deps: ['$ExitStatus', '$keepRuntimeAlive'],
 #endif
diff --git a/test/other/codesize/test_codesize_cxx_ctors1.gzsize b/test/other/codesize/test_codesize_cxx_ctors1.gzsize
index 732a842aa12a6..bdab782884e7c 100644
--- a/test/other/codesize/test_codesize_cxx_ctors1.gzsize
+++ b/test/other/codesize/test_codesize_cxx_ctors1.gzsize
@@ -1 +1 @@
-8475
+8472
diff --git a/test/other/codesize/test_codesize_cxx_ctors1.jssize b/test/other/codesize/test_codesize_cxx_ctors1.jssize
index 59348217ae934..5c6b69f267b0b 100644
--- a/test/other/codesize/test_codesize_cxx_ctors1.jssize
+++ b/test/other/codesize/test_codesize_cxx_ctors1.jssize
@@ -1 +1 @@
-20806
+20767
diff --git a/test/other/codesize/test_codesize_cxx_ctors2.gzsize b/test/other/codesize/test_codesize_cxx_ctors2.gzsize
index 90f694341a815..ef1ec3d26c2c1 100644
--- a/test/other/codesize/test_codesize_cxx_ctors2.gzsize
+++ b/test/other/codesize/test_codesize_cxx_ctors2.gzsize
@@ -1 +1 @@
-8456
+8453
diff --git a/test/other/codesize/test_codesize_cxx_ctors2.jssize b/test/other/codesize/test_codesize_cxx_ctors2.jssize
index ad46613b9ed79..6093276be9d72 100644
--- a/test/other/codesize/test_codesize_cxx_ctors2.jssize
+++ b/test/other/codesize/test_codesize_cxx_ctors2.jssize
@@ -1 +1 @@
-20774
+20735
diff --git a/test/other/codesize/test_codesize_cxx_except.gzsize b/test/other/codesize/test_codesize_cxx_except.gzsize
index 520a8359c3d9c..4eea0f3a6687c 100644
--- a/test/other/codesize/test_codesize_cxx_except.gzsize
+++ b/test/other/codesize/test_codesize_cxx_except.gzsize
@@ -1 +1 @@
-9500
+9499
diff --git a/test/other/codesize/test_codesize_cxx_except.jssize b/test/other/codesize/test_codesize_cxx_except.jssize
index 30b8fbb4af80d..38cbc8e8ce881 100644
--- a/test/other/codesize/test_codesize_cxx_except.jssize
+++ b/test/other/codesize/test_codesize_cxx_except.jssize
@@ -1 +1 @@
-24650
+24611
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm.gzsize b/test/other/codesize/test_codesize_cxx_except_wasm.gzsize
index 3a402b492b0d7..5e15f114c79fb 100644
--- a/test/other/codesize/test_codesize_cxx_except_wasm.gzsize
+++ b/test/other/codesize/test_codesize_cxx_except_wasm.gzsize
@@ -1 +1 @@
-8436
+8431
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm.jssize b/test/other/codesize/test_codesize_cxx_except_wasm.jssize
index 13c91e65d2408..e31823e04344c 100644
--- a/test/other/codesize/test_codesize_cxx_except_wasm.jssize
+++ b/test/other/codesize/test_codesize_cxx_except_wasm.jssize
@@ -1 +1 @@
-20699
+20660
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize b/test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize
index 3a402b492b0d7..5e15f114c79fb 100644
--- a/test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize
+++ b/test/other/codesize/test_codesize_cxx_except_wasm_exnref.gzsize
@@ -1 +1 @@
-8436
+8431
diff --git a/test/other/codesize/test_codesize_cxx_except_wasm_exnref.jssize b/test/other/codesize/test_codesize_cxx_except_wasm_exnref.jssize
index 13c91e65d2408..e31823e04344c 100644
--- a/test/other/codesize/test_codesize_cxx_except_wasm_exnref.jssize
+++ b/test/other/codesize/test_codesize_cxx_except_wasm_exnref.jssize
@@ -1 +1 @@
-20699
+20660
diff --git a/test/other/codesize/test_codesize_cxx_lto.gzsize b/test/other/codesize/test_codesize_cxx_lto.gzsize
index 477a586314ed3..1c35f29ce93d9 100644
--- a/test/other/codesize/test_codesize_cxx_lto.gzsize
+++ b/test/other/codesize/test_codesize_cxx_lto.gzsize
@@ -1 +1 @@
-8364
+8365
diff --git a/test/other/codesize/test_codesize_cxx_lto.jssize b/test/other/codesize/test_codesize_cxx_lto.jssize
index 7b21b44e64131..b14f4b5c068a5 100644
--- a/test/other/codesize/test_codesize_cxx_lto.jssize
+++ b/test/other/codesize/test_codesize_cxx_lto.jssize
@@ -1 +1 @@
-20385
+20346
diff --git a/test/other/codesize/test_codesize_cxx_mangle.gzsize b/test/other/codesize/test_codesize_cxx_mangle.gzsize
index a9be28888a309..ca7a892146d59 100644
--- a/test/other/codesize/test_codesize_cxx_mangle.gzsize
+++ b/test/other/codesize/test_codesize_cxx_mangle.gzsize
@@ -1 +1 @@
-9505
+9502
diff --git a/test/other/codesize/test_codesize_cxx_mangle.jssize b/test/other/codesize/test_codesize_cxx_mangle.jssize
index e9737da1ce9cc..ae9477568010b 100644
--- a/test/other/codesize/test_codesize_cxx_mangle.jssize
+++ b/test/other/codesize/test_codesize_cxx_mangle.jssize
@@ -1 +1 @@
-24651
+24612
diff --git a/test/other/codesize/test_codesize_cxx_noexcept.gzsize b/test/other/codesize/test_codesize_cxx_noexcept.gzsize
index 732a842aa12a6..bdab782884e7c 100644
--- a/test/other/codesize/test_codesize_cxx_noexcept.gzsize
+++ b/test/other/codesize/test_codesize_cxx_noexcept.gzsize
@@ -1 +1 @@
-8475
+8472
diff --git a/test/other/codesize/test_codesize_cxx_noexcept.jssize b/test/other/codesize/test_codesize_cxx_noexcept.jssize
index 59348217ae934..5c6b69f267b0b 100644
--- a/test/other/codesize/test_codesize_cxx_noexcept.jssize
+++ b/test/other/codesize/test_codesize_cxx_noexcept.jssize
@@ -1 +1 @@
-20806
+20767
diff --git a/test/other/codesize/test_codesize_cxx_wasmfs.gzsize b/test/other/codesize/test_codesize_cxx_wasmfs.gzsize
index b2c038c3bdd06..33196dc99838a 100644
--- a/test/other/codesize/test_codesize_cxx_wasmfs.gzsize
+++ b/test/other/codesize/test_codesize_cxx_wasmfs.gzsize
@@ -1 +1 @@
-3900
+3903
diff --git a/test/other/codesize/test_codesize_cxx_wasmfs.jssize b/test/other/codesize/test_codesize_cxx_wasmfs.jssize
index eb83661a0b8c1..a32df27cb8771 100644
--- a/test/other/codesize/test_codesize_cxx_wasmfs.jssize
+++ b/test/other/codesize/test_codesize_cxx_wasmfs.jssize
@@ -1 +1 @@
-8633
+8638
diff --git a/test/other/codesize/test_codesize_files_js_fs.gzsize b/test/other/codesize/test_codesize_files_js_fs.gzsize
index b69eaab75d21a..49b2da6655ab9 100644
--- a/test/other/codesize/test_codesize_files_js_fs.gzsize
+++ b/test/other/codesize/test_codesize_files_js_fs.gzsize
@@ -1 +1 @@
-7600
+7601
diff --git a/test/other/codesize/test_codesize_files_js_fs.jssize b/test/other/codesize/test_codesize_files_js_fs.jssize
index 6fc6a64238afb..0351a114bbe9a 100644
--- a/test/other/codesize/test_codesize_files_js_fs.jssize
+++ b/test/other/codesize/test_codesize_files_js_fs.jssize
@@ -1 +1 @@
-18701
+18662
diff --git a/test/other/codesize/test_codesize_files_wasmfs.gzsize b/test/other/codesize/test_codesize_files_wasmfs.gzsize
index 2ef62099534f6..00eda6ef936d1 100644
--- a/test/other/codesize/test_codesize_files_wasmfs.gzsize
+++ b/test/other/codesize/test_codesize_files_wasmfs.gzsize
@@ -1 +1 @@
-2981
+2993
diff --git a/test/other/codesize/test_codesize_files_wasmfs.jssize b/test/other/codesize/test_codesize_files_wasmfs.jssize
index f53dac545bf75..d2f62da3ce3c2 100644
--- a/test/other/codesize/test_codesize_files_wasmfs.jssize
+++ b/test/other/codesize/test_codesize_files_wasmfs.jssize
@@ -1 +1 @@
-6270
+6275
diff --git a/test/other/codesize/test_codesize_hello_O0.gzsize b/test/other/codesize/test_codesize_hello_O0.gzsize
index cdf8e565bdf9c..0d7889080c9fa 100644
--- a/test/other/codesize/test_codesize_hello_O0.gzsize
+++ b/test/other/codesize/test_codesize_hello_O0.gzsize
@@ -1 +1 @@
-8016
+8032
diff --git a/test/other/codesize/test_codesize_hello_O0.jssize b/test/other/codesize/test_codesize_hello_O0.jssize
index 2df1c8d05f0c0..d9ccc54644ba4 100644
--- a/test/other/codesize/test_codesize_hello_O0.jssize
+++ b/test/other/codesize/test_codesize_hello_O0.jssize
@@ -1 +1 @@
-21307
+21321
diff --git a/test/other/codesize/test_codesize_hello_O1.gzsize b/test/other/codesize/test_codesize_hello_O1.gzsize
index 4d86a0941c7cc..1d6219b116cab 100644
--- a/test/other/codesize/test_codesize_hello_O1.gzsize
+++ b/test/other/codesize/test_codesize_hello_O1.gzsize
@@ -1 +1 @@
-2803
+2816
diff --git a/test/other/codesize/test_codesize_hello_O1.jssize b/test/other/codesize/test_codesize_hello_O1.jssize
index 44b993cb696cf..3de258dcc34a7 100644
--- a/test/other/codesize/test_codesize_hello_O1.jssize
+++ b/test/other/codesize/test_codesize_hello_O1.jssize
@@ -1 +1 @@
-6918
+6932
diff --git a/test/other/codesize/test_codesize_hello_O2.gzsize b/test/other/codesize/test_codesize_hello_O2.gzsize
index bf6937821e4d1..ea908ff33b176 100644
--- a/test/other/codesize/test_codesize_hello_O2.gzsize
+++ b/test/other/codesize/test_codesize_hello_O2.gzsize
@@ -1 +1 @@
-2490
+2503
diff --git a/test/other/codesize/test_codesize_hello_O2.jssize b/test/other/codesize/test_codesize_hello_O2.jssize
index 0edc333521e2f..f96bb2f7a5857 100644
--- a/test/other/codesize/test_codesize_hello_O2.jssize
+++ b/test/other/codesize/test_codesize_hello_O2.jssize
@@ -1 +1 @@
-4977
+4982
diff --git a/test/other/codesize/test_codesize_hello_O3.gzsize b/test/other/codesize/test_codesize_hello_O3.gzsize
index 1415bc57370d0..3244ffd4e2090 100644
--- a/test/other/codesize/test_codesize_hello_O3.gzsize
+++ b/test/other/codesize/test_codesize_hello_O3.gzsize
@@ -1 +1 @@
-2408
+2419
diff --git a/test/other/codesize/test_codesize_hello_O3.jssize b/test/other/codesize/test_codesize_hello_O3.jssize
index cbf64eaf61f45..61dcbb9b95299 100644
--- a/test/other/codesize/test_codesize_hello_O3.jssize
+++ b/test/other/codesize/test_codesize_hello_O3.jssize
@@ -1 +1 @@
-4823
+4828
diff --git a/test/other/codesize/test_codesize_hello_Os.gzsize b/test/other/codesize/test_codesize_hello_Os.gzsize
index 1415bc57370d0..3244ffd4e2090 100644
--- a/test/other/codesize/test_codesize_hello_Os.gzsize
+++ b/test/other/codesize/test_codesize_hello_Os.gzsize
@@ -1 +1 @@
-2408
+2419
diff --git a/test/other/codesize/test_codesize_hello_Os.jssize b/test/other/codesize/test_codesize_hello_Os.jssize
index cbf64eaf61f45..61dcbb9b95299 100644
--- a/test/other/codesize/test_codesize_hello_Os.jssize
+++ b/test/other/codesize/test_codesize_hello_Os.jssize
@@ -1 +1 @@
-4823
+4828
diff --git a/test/other/codesize/test_codesize_hello_Oz.gzsize b/test/other/codesize/test_codesize_hello_Oz.gzsize
index edcb6c1945d2c..a0198be084430 100644
--- a/test/other/codesize/test_codesize_hello_Oz.gzsize
+++ b/test/other/codesize/test_codesize_hello_Oz.gzsize
@@ -1 +1 @@
-2387
+2400
diff --git a/test/other/codesize/test_codesize_hello_Oz.jssize b/test/other/codesize/test_codesize_hello_Oz.jssize
index cc7b31a6942b3..5352d47c64d98 100644
--- a/test/other/codesize/test_codesize_hello_Oz.jssize
+++ b/test/other/codesize/test_codesize_hello_Oz.jssize
@@ -1 +1 @@
-4789
+4794
diff --git a/test/other/codesize/test_codesize_hello_dylink.gzsize b/test/other/codesize/test_codesize_hello_dylink.gzsize
index 45c422c4a502c..de3d8348049da 100644
--- a/test/other/codesize/test_codesize_hello_dylink.gzsize
+++ b/test/other/codesize/test_codesize_hello_dylink.gzsize
@@ -1 +1 @@
-6328
+6340
diff --git a/test/other/codesize/test_codesize_hello_dylink.jssize b/test/other/codesize/test_codesize_hello_dylink.jssize
index da55b55b7b35b..a20d3e9da0ac7 100644
--- a/test/other/codesize/test_codesize_hello_dylink.jssize
+++ b/test/other/codesize/test_codesize_hello_dylink.jssize
@@ -1 +1 @@
-13877
+13882
diff --git a/test/other/codesize/test_codesize_hello_wasmfs.gzsize b/test/other/codesize/test_codesize_hello_wasmfs.gzsize
index 1415bc57370d0..3244ffd4e2090 100644
--- a/test/other/codesize/test_codesize_hello_wasmfs.gzsize
+++ b/test/other/codesize/test_codesize_hello_wasmfs.gzsize
@@ -1 +1 @@
-2408
+2419
diff --git a/test/other/codesize/test_codesize_hello_wasmfs.jssize b/test/other/codesize/test_codesize_hello_wasmfs.jssize
index cbf64eaf61f45..61dcbb9b95299 100644
--- a/test/other/codesize/test_codesize_hello_wasmfs.jssize
+++ b/test/other/codesize/test_codesize_hello_wasmfs.jssize
@@ -1 +1 @@
-4823
+4828
diff --git a/test/other/codesize/test_codesize_libcxxabi_message_O3.gzsize b/test/other/codesize/test_codesize_libcxxabi_message_O3.gzsize
index 77a4a378039b1..54ece5b58e987 100644
--- a/test/other/codesize/test_codesize_libcxxabi_message_O3.gzsize
+++ b/test/other/codesize/test_codesize_libcxxabi_message_O3.gzsize
@@ -1 +1 @@
-1961
+1974
diff --git a/test/other/codesize/test_codesize_libcxxabi_message_O3.jssize b/test/other/codesize/test_codesize_libcxxabi_message_O3.jssize
index 24b2d1ddd384c..094b123f88fb8 100644
--- a/test/other/codesize/test_codesize_libcxxabi_message_O3.jssize
+++ b/test/other/codesize/test_codesize_libcxxabi_message_O3.jssize
@@ -1 +1 @@
-4044
+4049
diff --git a/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize b/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize
index 1ff838f1b4cd7..48ad625d0644d 100644
--- a/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize
+++ b/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.gzsize
@@ -1 +1 @@
-1998
+2010
diff --git a/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize b/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize
index d96a36c7bcde2..e11a7374b2ca3 100644
--- a/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize
+++ b/test/other/codesize/test_codesize_libcxxabi_message_O3_standalone.jssize
@@ -1 +1 @@
-4093
+4098
diff --git a/test/other/codesize/test_codesize_mem_O3.gzsize b/test/other/codesize/test_codesize_mem_O3.gzsize
index 8b024ea4025d7..6d92b9495f826 100644
--- a/test/other/codesize/test_codesize_mem_O3.gzsize
+++ b/test/other/codesize/test_codesize_mem_O3.gzsize
@@ -1 +1 @@
-2421
+2431
diff --git a/test/other/codesize/test_codesize_mem_O3.jssize b/test/other/codesize/test_codesize_mem_O3.jssize
index 5f6bce5b73469..386dbe73c9173 100644
--- a/test/other/codesize/test_codesize_mem_O3.jssize
+++ b/test/other/codesize/test_codesize_mem_O3.jssize
@@ -1 +1 @@
-4966
+4971
diff --git a/test/other/codesize/test_codesize_mem_O3_grow.gzsize b/test/other/codesize/test_codesize_mem_O3_grow.gzsize
index b04af7c81b6a4..e2c12dfcdca3e 100644
--- a/test/other/codesize/test_codesize_mem_O3_grow.gzsize
+++ b/test/other/codesize/test_codesize_mem_O3_grow.gzsize
@@ -1 +1 @@
-2566
+2577
diff --git a/test/other/codesize/test_codesize_mem_O3_grow.jssize b/test/other/codesize/test_codesize_mem_O3_grow.jssize
index cc590acbac0d8..cc1d64bcf857b 100644
--- a/test/other/codesize/test_codesize_mem_O3_grow.jssize
+++ b/test/other/codesize/test_codesize_mem_O3_grow.jssize
@@ -1 +1 @@
-5248
+5253
diff --git a/test/other/codesize/test_codesize_mem_O3_grow_standalone.gzsize b/test/other/codesize/test_codesize_mem_O3_grow_standalone.gzsize
index b54ebd4f0806d..eb8c15407016f 100644
--- a/test/other/codesize/test_codesize_mem_O3_grow_standalone.gzsize
+++ b/test/other/codesize/test_codesize_mem_O3_grow_standalone.gzsize
@@ -1 +1 @@
-2263
+2274
diff --git a/test/other/codesize/test_codesize_mem_O3_grow_standalone.jssize b/test/other/codesize/test_codesize_mem_O3_grow_standalone.jssize
index 7a306370c3b7e..748cd1a12b5e6 100644
--- a/test/other/codesize/test_codesize_mem_O3_grow_standalone.jssize
+++ b/test/other/codesize/test_codesize_mem_O3_grow_standalone.jssize
@@ -1 +1 @@
-4654
+4659
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone.gzsize b/test/other/codesize/test_codesize_mem_O3_standalone.gzsize
index c7dc989f8044a..f9bef4af2873b 100644
--- a/test/other/codesize/test_codesize_mem_O3_standalone.gzsize
+++ b/test/other/codesize/test_codesize_mem_O3_standalone.gzsize
@@ -1 +1 @@
-2222
+2233
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone.jssize b/test/other/codesize/test_codesize_mem_O3_standalone.jssize
index 549fc8c576ee3..0da8daf710b2c 100644
--- a/test/other/codesize/test_codesize_mem_O3_standalone.jssize
+++ b/test/other/codesize/test_codesize_mem_O3_standalone.jssize
@@ -1 +1 @@
-4584
+4589
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_lib.gzsize b/test/other/codesize/test_codesize_mem_O3_standalone_lib.gzsize
index 568aaf43d83b2..44173d5cb77fe 100644
--- a/test/other/codesize/test_codesize_mem_O3_standalone_lib.gzsize
+++ b/test/other/codesize/test_codesize_mem_O3_standalone_lib.gzsize
@@ -1 +1 @@
-1984
+1996
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_lib.jssize b/test/other/codesize/test_codesize_mem_O3_standalone_lib.jssize
index 50b0f79069f1e..d7df15d1cdfb2 100644
--- a/test/other/codesize/test_codesize_mem_O3_standalone_lib.jssize
+++ b/test/other/codesize/test_codesize_mem_O3_standalone_lib.jssize
@@ -1 +1 @@
-4095
+4100
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_narg.gzsize b/test/other/codesize/test_codesize_mem_O3_standalone_narg.gzsize
index 1ff838f1b4cd7..48ad625d0644d 100644
--- a/test/other/codesize/test_codesize_mem_O3_standalone_narg.gzsize
+++ b/test/other/codesize/test_codesize_mem_O3_standalone_narg.gzsize
@@ -1 +1 @@
-1998
+2010
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_narg.jssize b/test/other/codesize/test_codesize_mem_O3_standalone_narg.jssize
index d96a36c7bcde2..e11a7374b2ca3 100644
--- a/test/other/codesize/test_codesize_mem_O3_standalone_narg.jssize
+++ b/test/other/codesize/test_codesize_mem_O3_standalone_narg.jssize
@@ -1 +1 @@
-4093
+4098
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize b/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize
index 1ff838f1b4cd7..48ad625d0644d 100644
--- a/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize
+++ b/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.gzsize
@@ -1 +1 @@
-1998
+2010
diff --git a/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize b/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize
index d96a36c7bcde2..e11a7374b2ca3 100644
--- a/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize
+++ b/test/other/codesize/test_codesize_mem_O3_standalone_narg_flto.jssize
@@ -1 +1 @@
-4093
+4098
diff --git a/test/other/codesize/test_codesize_minimal_pthreads.gzsize b/test/other/codesize/test_codesize_minimal_pthreads.gzsize
index a4c77792658e9..05166d8462423 100644
--- a/test/other/codesize/test_codesize_minimal_pthreads.gzsize
+++ b/test/other/codesize/test_codesize_minimal_pthreads.gzsize
@@ -1 +1 @@
-4722
+4735
diff --git a/test/other/codesize/test_codesize_minimal_pthreads.jssize b/test/other/codesize/test_codesize_minimal_pthreads.jssize
index a58b0aed39a8c..0b713b42c5542 100644
--- a/test/other/codesize/test_codesize_minimal_pthreads.jssize
+++ b/test/other/codesize/test_codesize_minimal_pthreads.jssize
@@ -1 +1 @@
-9949
+9954
diff --git a/test/other/test_unoptimized_code_size.js.size b/test/other/test_unoptimized_code_size.js.size
index 3d39cb3e3ff95..4900d73773e5d 100644
--- a/test/other/test_unoptimized_code_size.js.size
+++ b/test/other/test_unoptimized_code_size.js.size
@@ -1 +1 @@
-54871
+54876
diff --git a/test/other/test_unoptimized_code_size_no_asserts.js.size b/test/other/test_unoptimized_code_size_no_asserts.js.size
index ddff8a6fb02fb..a8ff86faa1431 100644
--- a/test/other/test_unoptimized_code_size_no_asserts.js.size
+++ b/test/other/test_unoptimized_code_size_no_asserts.js.size
@@ -1 +1 @@
-30527
+30529
diff --git a/test/other/test_unoptimized_code_size_strict.js.size b/test/other/test_unoptimized_code_size_strict.js.size
index ea3b7230a5248..3dbe8359fb262 100644
--- a/test/other/test_unoptimized_code_size_strict.js.size
+++ b/test/other/test_unoptimized_code_size_strict.js.size
@@ -1 +1 @@
-53745
+53785
diff --git a/tools/acorn-optimizer.mjs b/tools/acorn-optimizer.mjs
index bd7b3e067a7e0..e5e36f55edd11 100755
--- a/tools/acorn-optimizer.mjs
+++ b/tools/acorn-optimizer.mjs
@@ -2037,8 +2037,7 @@ if (extraInfoStart > 0) {
 // outputted code if --closureFriendly was requested.
 const sourceComments = {};
 const params = {
-  // Keep in sync with --language_in that we pass to closure in building.py
-  ecmaVersion: 2021,
+  ecmaVersion: 'latest',
   sourceType: exportES6 ? 'module' : 'script',
   allowAwaitOutsideFunction: true,
 };
diff --git a/tools/building.py b/tools/building.py
index 3801f56b0f875..5559b7c170603 100644
--- a/tools/building.py
+++ b/tools/building.py
@@ -593,8 +593,7 @@ def closure_compiler(filename, advanced=True, extra_closure_args=None):
     CLOSURE_EXTERNS += [path_from_root('src/closure-externs/dyncall-externs.js')]
 
   args = ['--compilation_level', 'ADVANCED_OPTIMIZATIONS' if advanced else 'SIMPLE_OPTIMIZATIONS']
-  # Keep in sync with ecmaVersion in tools/acorn-optimizer.mjs
-  args += ['--language_in', 'ECMASCRIPT_2021']
+  args += ['--language_in', 'UNSTABLE']
   # We do transpilation using babel
   args += ['--language_out', 'NO_TRANSPILE']
   # Tell closure never to inject the 'use strict' directive.