Some cleanups to Frog to avoid looking up its builtin types too much

frog/library.dart

 // Copyright (c) 2011, 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.
 
 class LibraryImport {
   String prefix;
   Library library;
   LibraryImport(this.library, [this.prefix = null]);
 }
 
@@ skipping 26 matching lines @@
   }
 
   Element get enclosingElement() => null;
   Library get library() => this;
 
   bool get isNative() => topType.isNative;
 
   bool get isCore() => this == world.corelib;
   bool get isCoreImpl() => this == world.coreimpl;
 
+  // TODO(jmesserly): we shouldn't be special casing DOM anywhere.
+  bool get isDom() => this == world.dom;
+
   SourceSpan get span() => new SourceSpan(baseSource, 0, 0);
 
   String makeFullPath(String filename) {
     if (filename.startsWith('dart:')) return filename;
     // TODO(jmesserly): replace with node.js path.resolve
     if (filename.startsWith('/')) return filename;
     if (filename.startsWith('file:///')) return filename;
     if (filename.startsWith('http://')) return filename;
     return joinPaths(sourceDir, filename);
   }
@@ skipping 58 matching lines @@
     m.resolve();
     // Function types implement the Function interface.
     type.interfaces = [world.functionType];
     return type;
   }
 
   /** Adds a type to the library. */
   DefinedType addType(String name, Node definition, bool isClass) {
     if (types.containsKey(name)) {
       var existingType = types[name];
-      if (isCore && existingType.definition == null) {
+      if ((isCore || isCoreImpl) && existingType.definition == null) {
         // TODO(jimhug): Validate compatibility with natives.
         existingType.setDefinition(definition);
       } else {
         world.warning('duplicate definition of $name', definition.span,
             existingType.span);
       }
     } else {
       types[name] = new DefinedType(name, this, definition, isClass);
     }
 
@@ skipping 344 matching lines @@
 
   void visitFunctionDefinition(FunctionDefinition node) {
     currentType.addMethod(node.name.name, node);
   }
 
   void visitFunctionTypeDefinition(FunctionTypeDefinition node) {
     var type = library.addType(node.func.name.name, node, false);
     type.addMethod(':call', node.func);
   }
 }