Allow patch files to add top-level declarations to the patched library.

lib/compiler/implementation/resolver.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.
 
 interface TreeElements {
   Element operator[](Node node);
   Selector getSelector(Send send);
   Type getType(TypeAnnotation annotation);
 }
 
@@ skipping 1849 matching lines @@
 }
 
 class VariableDefinitionsVisitor extends CommonResolverVisitor<SourceString> {
   VariableDefinitions definitions;
   ResolverVisitor resolver;
   ElementKind kind;
   VariableListElement variables;
 
   VariableDefinitionsVisitor(Compiler compiler,
                              this.definitions, this.resolver, this.kind)
-    : super(compiler)
-  {
+      : super(compiler) {
     variables = new VariableListElement.node(
         definitions, ElementKind.VARIABLE_LIST, resolver.context.element);
   }
 
   SourceString visitSendSet(SendSet node) {
     assert(node.arguments.tail.isEmpty()); // Sanity check
     resolver.visit(node.arguments.head);
     return visit(node.selector);
   }
 
@@ skipping 323 matching lines @@
 
   TopScope(LibraryElement library) : super(null, library);
   Element lookup(SourceString name) {
     return library.find(name);
   }
 
   Element add(Element newElement) {
     throw "Cannot add an element in the top scope";
   }
 }