dart2js: fail gracefully with invalid package config

Fixes #24118
Fixes #24120
Fixes #24121
Fixes #24122

BUG=
R=sigmund@google.com

Review URL: https://codereview.chromium.org//1291283006 .

Author: harryterkelsen

pkg/compiler/lib/src/apiimpl.dart

@@ -394,13 +394,17 @@ class Compiler extends leg.Compiler {
         }
         // The input provider may put a trailing 0 byte when it reads a source
         // file, which confuses the package config parser.
-        if (packageConfigContents.length > 0
-            && packageConfigContents.last == 0) {
+        if (packageConfigContents.length > 0 &&
+            packageConfigContents.last == 0) {
           packageConfigContents = packageConfigContents.sublist(
               0, packageConfigContents.length - 1);
         }
         packages =
             new MapPackages(pkgs.parse(packageConfigContents, packageConfig));
+      }).catchError((error) {
+        reportError(NO_LOCATION_SPANNABLE, MessageKind.INVALID_PACKAGE_CONFIG,
+            {'uri': packageConfig, 'exception': error});
+        packages = Packages.noPackages;
       });
     } else {
       if (packagesDiscoveryProvider == null) {

pkg/compiler/lib/src/diagnostics/messages.dart

@@ -256,6 +256,7 @@ enum MessageKind {
   INVALID_OVERRIDE_METHOD,
   INVALID_OVERRIDE_SETTER,
   INVALID_OVERRIDE_SETTER_WITH_FIELD,
+  INVALID_PACKAGE_CONFIG,
   INVALID_PACKAGE_URI,
   INVALID_PARAMETER,
   INVALID_RECEIVER_IN_INITIALIZER,
@@ -2233,6 +2234,13 @@ import '../../Udyn[mic ils/expect.dart';
 main() {}
 """]),
 
+      MessageKind.INVALID_PACKAGE_CONFIG:
+          const MessageTemplate(MessageKind.INVALID_PACKAGE_CONFIG,
+            """Package config file '#{uri}' is invalid.
+#{exception}""",
+            howToFix: DONT_KNOW_HOW_TO_FIX
+      ),
+
       MessageKind.INVALID_PACKAGE_URI:
         const MessageTemplate(MessageKind.INVALID_PACKAGE_URI,
           "'#{uri}' is not a valid package URI (#{exception}).",

tests/standalone/standalone.status

@@ -100,10 +100,6 @@ javascript_compatibility_errors_test: Skip
 javascript_compatibility_warnings_test: Skip
 unboxed_int_converter_test: Skip
 pair_location_remapping_test: Skip
-package/scenarios/invalid/non_existent_packages_file_test: Crash # Issue 24118
-package/scenarios/invalid/invalid_utf8_test: Crash # Issue 24120
-package/scenarios/invalid/invalid_package_name_test: Crash # Issue 24121
-package/scenarios/invalid/same_package_twice_test: Crash # Issue 24122
 
 [ $compiler == dart2js && $jscl ]
 assert_test: RuntimeError, OK # Assumes unspecified fields on the AssertionError.