Source in most stuff.

dart/frog/leg/lib/js_helper.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.
 
 #library('js_helper');
 
-#import('core.dart');
-
 $throw(String msg) {
   var e = JS("Object", @"new Error($0)", msg);
   var hasTrace = JS("bool", @"Error.captureStackTrace !== (void 0)");
   if (hasTrace) {
     JS("void", @"Error.captureStackTrace($0)", e);
   }
   throw e;
 }
 
 /**
@@ skipping 271 matching lines @@
     return UNINTERCEPTED(receiver.charCodeAt(index));
   }
 }
 
 builtin$isEmpty$0(var receiver) {
   if (receiver is String || isJSArray(receiver)) {
     return JS("bool", @"$0.length === 0", receiver);
   }
   return UNINTERCEPTED(receiver.isEmpty());
 }