Fix handling of async patches.

pkg/compiler/lib/src/elements/modelx.dart

 // Copyright (c) 2013, 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 elements.modelx;
 
 import '../common.dart';
 import '../common/names.dart' show Identifiers;
 import '../common/resolution.dart' show Resolution, ParsingContext;
 import '../compiler.dart' show Compiler;
@@ skipping 323 matching lines @@
   get asyncMarker {
     throw new UnsupportedError("asyncMarker");
   }
 
   @override
   set asyncMarker(_) {
     throw new UnsupportedError("asyncMarker=");
   }
 
   @override
+  get _asyncMarker {
+    throw new UnsupportedError("_asyncMarker");
+  }
+
+  @override
+  set _asyncMarker(_) {
+    throw new UnsupportedError("_asyncMarker=");
+  }
+
+  @override
   get effectiveTargetInternal {
     throw new UnsupportedError("effectiveTargetInternal");
   }
 
   @override
   set effectiveTargetInternal(_) {
     throw new UnsupportedError("effectiveTargetInternal=");
   }
 
   @override
@@ skipping 1684 matching lines @@
 abstract class BaseFunctionElementX extends ElementX
     with PatchMixin<FunctionElement>, AstElementMixin
     implements FunctionElement {
   ResolutionDartType typeCache;
   final Modifiers modifiers;
 
   List<FunctionElement> nestedClosures = new List<FunctionElement>();
 
   FunctionSignature _functionSignatureCache;
 
-  AsyncMarker asyncMarker = AsyncMarker.SYNC;
+  AsyncMarker _asyncMarker = AsyncMarker.SYNC;
 
   BaseFunctionElementX(String name, ElementKind kind, Modifiers this.modifiers,
       Element enclosing)
       : super(name, kind, enclosing) {
     assert(modifiers != null);
   }
 
+  AsyncMarker get asyncMarker {
+    if (isPatched) {
+      return patch.asyncMarker;
+    }
+    return _asyncMarker;
+  }
+
+  void set asyncMarker(AsyncMarker value) {
+    if (isPatched) {
+      BaseFunctionElementX function = patch;
+      function.asyncMarker = value;
+    } else {
+      _asyncMarker = value;
+    }
+  }
+
   bool get isExternal => modifiers.isExternal;
 
   bool get isInstanceMember {
     return isClassMember && !isConstructor && !isStatic;
   }
 
   ParameterStructure get parameterStructure =>
       functionSignature.parameterStructure;
 
   bool get hasFunctionSignature => _functionSignatureCache != null;
@@ skipping 1509 matching lines @@
       body = node.asFunctionExpression().body;
     }
     return new ParsedResolvedAst(
         declaration,
         node,
         body,
         definingElement.treeElements,
         definingElement.compilationUnit.script.resourceUri);
   }
 }