Emscripten: Turn wasm-eh on by default

As specified by MCP:
rust-lang/compiler-team#920
Resolves #148309

Author: hoodmane

compiler/rustc_interface/src/tests.rs

@@ -796,7 +796,7 @@ fn test_unstable_options_tracking_hash() {
     tracked!(embed_metadata, false);
     tracked!(embed_source, true);
     tracked!(emit_thin_lto, false);
-    tracked!(emscripten_wasm_eh, true);
+    tracked!(emscripten_wasm_eh, false);
     tracked!(export_executable_symbols, true);
     tracked!(fewer_names, Some(true));
     tracked!(fixed_x18, true);

compiler/rustc_session/src/options.rs

@@ -2307,7 +2307,7 @@ options! {
         "emit a section containing stack size metadata (default: no)"),
     emit_thin_lto: bool = (true, parse_bool, [TRACKED],
         "emit the bc module with thin LTO info (default: yes)"),
-    emscripten_wasm_eh: bool = (false, parse_bool, [TRACKED],
+    emscripten_wasm_eh: bool = (true, parse_bool, [TRACKED],
         "Use WebAssembly error handling for wasm32-unknown-emscripten"),
     enforce_type_length_limit: bool = (false, parse_bool, [TRACKED],
         "enforce the type length limit when monomorphizing instances in codegen"),