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

frog/var_member.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.
 
 /** A dynamic member stub. */
 class VarMember {
   final String name;
   bool isGenerated = false;
 
   VarMember(this.name);
@@ skipping 51 matching lines @@
 // TODO(jmesserly): _genStub is a hole in the run-time type checker.
 // It bypasses the checks we would do at the callsite for methods.
 // Also, it won't work properly for native JS functions (those don't have
 // an accurate .length)
 class VarFunctionStub extends VarMember {
   final Arguments args;
 
   VarFunctionStub(String name, Arguments callArgs)
     : super(name), args = callArgs.toCallStubArgs() {
     // Ensure dependency is generated
-    var funcImpl = world.coreimpl.types['_FunctionImplementation'];
-    funcImpl.markUsed();
-    world.gen.genMethod(funcImpl.getMember('_genStub'));
+    world.functionImplType.markUsed();
+    world.gen.genMethod(world.functionImplType.getMember('_genStub'));
   }
 
   Value invoke(MethodGenerator context, Node node, Value target,
       Arguments args) {
     return super.invoke(context, node, target, args);
   }
 
   void generate(CodeWriter code) {
     isGenerated = true;
     if (args.hasNames) {
@@ skipping 176 matching lines @@
     nameBuilder.add('\$');
     if (name.contains('\$')) {
       // Disambiguate "a:b:" from "a$b:".  Using the length works well because
       // the names can't start with digits.
       nameBuilder.add('${name.length}');
     }
     nameBuilder.add(name);
   }
   return nameBuilder.toString();
 }