Fix various parser bugs related to modifiers of top-level and class members.

dart/sdk/lib/_internal/compiler/implementation/patch_parser.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 library contains the infrastructure to parse and integrate patch files.
  *
  * Three types of elements can be patched: [LibraryElement], [ClassElement],
  * [FunctionElement]. Patches are introduced in patch libraries which are loaded
  * together with the corresponding origin library. Which libraries that are
@@ skipping 383 matching lines @@
                    Element patch) {
   if (origin == null) {
     listener.reportError(
         patch, leg.MessageKind.PATCH_NON_EXISTING, {'name': patch.name});
     return;
   }
   if (!(origin.isClass() ||
         origin.isConstructor() ||
         origin.isFunction() ||
         origin.isAbstractField())) {
+    // TODO(ahe): Remove this error when the parser rejects all bad modifiers.
     listener.reportError(origin, leg.MessageKind.PATCH_NONPATCHABLE);
     return;
   }
   if (patch.isClass()) {
     tryPatchClass(listener, origin, patch);
   } else if (patch.isGetter()) {
     tryPatchGetter(listener, origin, patch);
   } else if (patch.isSetter()) {
     tryPatchSetter(listener, origin, patch);
   } else if (patch.isConstructor()) {
     tryPatchConstructor(listener, origin, patch);
   } else if(patch.isFunction()) {
     tryPatchFunction(listener, origin, patch);
   } else {
+    // TODO(ahe): Remove this error when the parser rejects all bad modifiers.
     listener.reportError(patch, leg.MessageKind.PATCH_NONPATCHABLE);
   }
 }
 
 void tryPatchClass(leg.DiagnosticListener listener,
                     Element origin,
                     ClassElement patch) {
   if (!origin.isClass()) {
     listener.reportError(
         origin, leg.MessageKind.PATCH_NON_CLASS, {'className': patch.name});
@@ skipping 119 matching lines @@
 
 // TODO(johnniwinther): Add unittest when patch is (real) metadata.
 bool isPatchElement(Element element) {
   // TODO(lrn): More checks needed if we introduce metadata for real.
   // In that case, it must have the identifier "native" as metadata.
   for (Link link = element.metadata; !link.isEmpty; link = link.tail) {
     if (link.head is PatchMetadataAnnotation) return true;
   }
   return false;
 }