Make the VM's dart:core and dart:async library patches clean.

runtime/lib/core_patch.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.
 
 import "dart:async";
 import "dart:collection" show LinkedList, LinkedListEntry;
 import 'dart:convert' show ASCII, JSON;
 import "dart:isolate";
 import "dart:math";
 import "dart:typed_data";
 import 'dart:_internal' as internal;
 
 // Equivalent of calling FATAL from C++ code.
 _fatal(msg) native "DartCore_fatal";
 
 // The members of this class are cloned and added to each class that
 // represents an enum type.
 class _EnumHelper {
   String _name;
   String toString() => _name;
   int get hashCode => _name.hashCode;
 }
 
 // _SyncIterable and _syncIterator are used by the compiler to
 // implement sync* generator functions. A sync* generator allocates
 // and returns a new _SyncIterable object.
 
-typedef bool SyncGeneratorCallback(Iterator iterator);
+typedef bool _SyncGeneratorCallback(Iterator iterator);
 
 class _SyncIterable extends IterableBase {
-  // moveNextFn is the closurized body of the generator function.
-  final SyncGeneratorCallback moveNextFn;
+  // _moveNextFn is the closurized body of the generator function.
+  final _SyncGeneratorCallback _moveNextFn;
 
-  const _SyncIterable(this.moveNextFn);
+  const _SyncIterable(this._moveNextFn);
 
   get iterator {
-    return new _SyncIterator(moveNextFn._clone());
+    return new _SyncIterator(_moveNextFn._clone());
   }
 }
 
 class _SyncIterator implements Iterator {
   bool isYieldEach;  // Set by generated code for the yield* statement.
   Iterator yieldEachIterator;
   var _current;  // Set by generated code for the yield and yield* statement.
-  SyncGeneratorCallback moveNextFn;
+  _SyncGeneratorCallback _moveNextFn;
 
   get current => yieldEachIterator != null
       ? yieldEachIterator.current
       : _current;
 
-  _SyncIterator(this.moveNextFn);
+  _SyncIterator(this._moveNextFn);
 
   bool moveNext() {
-    if (moveNextFn == null) {
+    if (_moveNextFn == null) {
       return false;
     }
     while(true) {
       if (yieldEachIterator != null) {
         if (yieldEachIterator.moveNext()) {
           return true;
         }
         yieldEachIterator = null;
       }
       isYieldEach = false;
-      // moveNextFn() will update the values of isYieldEach and _current.
-      if (!moveNextFn(this)) {
-        moveNextFn = null;
+      // _moveNextFn() will update the values of isYieldEach and _current.
+      if (!_moveNextFn(this)) {
+        _moveNextFn = null;
         _current = null;
         return false;
       }
       if (isYieldEach) {
         // Spec mandates: it is a dynamic error if the class of [the object
         // returned by yield*] does not implement Iterable.
         yieldEachIterator = (_current as Iterable).iterator;
         _current = null;
         continue;
       }
       return true;
     }
   }
 }
 
 @patch class StackTrace {
   @patch static StackTrace get current native "StackTrace_current";
 }