dart2js: fix crash when annotations have syntax errors (fix #23983)

pkg/compiler/lib/src/compile_time_constants.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.
 
 library dart2js.compile_time_constant_evaluator;
 
 import 'constant_system_dart.dart';
 import 'constants/constant_system.dart';
 import 'constants/expressions.dart';
 import 'constants/values.dart';
@@ skipping 318 matching lines @@
 
   CompileTimeConstantEvaluator(this.handler,
                                this.elements,
                                this.compiler,
                                {bool isConst: false})
       : this.isEvaluatingConstant = isConst;
 
   ConstantSystem get constantSystem => handler.constantSystem;
 
   AstConstant evaluate(Node node) {
+    // TODO(johnniwinter): should there be a visitErrorNode?

[Johnni Winther, 2015/07/27 07:57:05]

'johnniwinter' -> 'johnniwinther' (but kudos for getting 'johnni' right :)

[Siggi Cherem (dart-lang), 2015/07/27 16:26:44]

Oh thanks for letting me know :) 

I forgot to include it when I submitted (I got confused and thought it was
another CL), but I sent a follow up change to fix it.

+    if (node is ErrorNode) return new ErroneousAstConstant(context, node);
     return node.accept(this);
   }
 
   AstConstant evaluateConstant(Node node) {
     bool oldIsEvaluatingConstant = isEvaluatingConstant;
     isEvaluatingConstant = true;
     AstConstant result = node.accept(this);
     isEvaluatingConstant = oldIsEvaluatingConstant;
     assert(result != null);
     return result;
@@ skipping 984 matching lines @@
           // TODO(johnniwinther): Return a [NonConstantValue] instead.
           new ErroneousConstantExpression(), new NullConstantValue());
 }
 
 // TODO(johnniwinther): Avoid the need for this hack.
 TreeElements _analyzeElementEagerly(Compiler compiler, AstElement element) {
   WorldImpact worldImpact = compiler.analyzeElement(element.declaration);
   compiler.enqueuer.resolution.applyImpact(element.declaration, worldImpact);
   return element.resolvedAst.elements;
 }