Recover from fatal parser errors.

dart/pkg/compiler/lib/src/use_unused_api.dart

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 /// This file use methods that aren't used by dart2js.dart, but that we wish to
 /// keep anyway. This might be general API that isn't currently in use,
 /// debugging aids, or API only used for testing (see TODO below).
 
 library dart2js.use_unused_api;
 
@@ skipping 23 matching lines @@
 
 import 'scanner/scannerlib.dart' show
     PartialClassElement,
     PartialFunctionElement;
 
 class ElementVisitor extends elements_visitor.ElementVisitor {
   visitElement(e) {}
 }
 
 void main(List<String> arguments) {
+  new dart2jslib.CompilerCancelledException(null);
   useApi();
   dart2js.main(arguments);
   useConstant(null, null);
   useNode(null);
   useUtil(null);
   useSetlet(null);
   useImmutableEmptySet(null);
   useElementVisitor(new ElementVisitor());
   useJs(new js.Program(null));
   useJs(new js.Blob(null));
@@ skipping 214 matching lines @@
   new dart_types.ResolvedTypedefType(null, null, null).unalias(null);
 }
 
 useCodeEmitterTask(js_emitter.CodeEmitterTask codeEmitterTask) {
   codeEmitterTask.oldEmitter.clearCspPrecompiledNodes();
 }
 
 useScript(dart2jslib.Script script) {
   script.copyWithFile(null);
 }