Alternative fix for the js-interop crash.

pkg/compiler/lib/src/dart2js.dart

Index: pkg/compiler/lib/src/dart2js.dart
diff --git a/pkg/compiler/lib/src/dart2js.dart b/pkg/compiler/lib/src/dart2js.dart
index fa7aeb734416f54622013c9333148631401373e8..662316bcd69ac7196a889f7acc55f2b44a05618d 100644
--- a/pkg/compiler/lib/src/dart2js.dart
+++ b/pkg/compiler/lib/src/dart2js.dart
@@ -119,6 +119,7 @@ Future<api.CompilationResult> compile(List<String> argv) {
   bool dumpInfo = false;
   bool allowNativeExtensions = false;
   bool trustTypeAnnotations = false;
+  bool trustJSInteropTypeAnnotations = false;
   bool checkedMode = false;
   // List of provided options that imply that output is expected.
   List<String> optionsImplyCompilation = <String>[];
@@ -227,6 +228,11 @@ Future<api.CompilationResult> compile(List<String> argv) {
     implyCompilation(argument);
   }
 
+  setTrustJSInteropTypeAnnotations(String argument) {
+    trustJSInteropTypeAnnotations = true;
+    implyCompilation(argument);
+  }
+
   setTrustPrimitives(String argument) {
     implyCompilation(argument);
   }
@@ -326,6 +332,9 @@ Future<api.CompilationResult> compile(List<String> argv) {
     new OptionHandler(Flags.trustPrimitives,
                       (_) => setTrustPrimitives(
                           Flags.trustPrimitives)),
+    new OptionHandler(Flags.trustJSInteropTypeAnnotations,
+                      (_) => setTrustJSInteropTypeAnnotations(
+                          Flags.trustJSInteropTypeAnnotations)),
     new OptionHandler(r'--help|/\?|/h', (_) => wantHelp = true),
     new OptionHandler('--packages=.+', setPackageConfig),
     new OptionHandler('--package-root=.+|-p.+', setPackageRoot),