Move JSSyntaxRegExp to core as a private member. This removes the last refrences to dart:coreimpl.

compiler/java/com/google/dart/compiler/resolver/Elements.java

 // 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.
 
 package com.google.dart.compiler.resolver;
 
 import com.google.common.annotations.VisibleForTesting;
 import com.google.common.base.Objects;
 import com.google.common.collect.Iterables;
 import com.google.common.collect.Lists;
@@ skipping 743 matching lines @@
   public static boolean isCoreLibrarySource(Source source) {
     if (source != null && source.getUri() != null
         && source.getUri().toString().equals("libraries.dart")) {
       return true;
     }
     // TODO (danrubel) remove these when dartc libraries are removed
     // Old core library file names
     return Elements.isLibrarySource(source, "/core/corelib.dart")
         || Elements.isLibrarySource(source, "/core/corelib_impl.dart")
         // New core library file names
-        || Elements.isLibrarySource(source, "/core/core.dart")
-        || Elements.isLibrarySource(source, "/core/coreimpl.dart")
-        || Elements.isLibrarySource(source, "/coreimpl/coreimpl.dart");
+        || Elements.isLibrarySource(source, "/core/core.dart");
   }
   
   public static boolean isHtmlLibrarySource(Source source) {
     return Elements.isLibrarySource(source, "/html/dartium/html_dartium.dart");
   }
 
   /**
    * @return the {@link LibraryElement} which declares given {@link Element}.
    */
   public static LibraryElement getDeclaringLibrary(Element element) {
@@ skipping 110 matching lines @@
     {
       InterfaceType superType = classElement.getSupertype();
       if (superType != null)
         addAllMembers(visited, allMembers, superType.getElement());
     }
     for (InterfaceType intf : classElement.getInterfaces()) {
       addAllMembers(visited, allMembers, intf.getElement());
     }
   }
 }