fixes detection of SDK libraries

lib/src/utils.dart

 // Copyright (c) 2015, 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.
 
 /// Holds a couple utility functions used at various places in the system.
 library dev_compiler.src.utils;
 
 import 'dart:io';
 
 import 'package:path/path.dart' as path;
@@ skipping 447 matching lines @@
   int lineEnd = endLoc.offset;
   int unitEnd = unit.endToken.end;
   int lineNum = lineInfo.getLocation(lineEnd).lineNumber;
   while (lineEnd < unitEnd &&
       lineInfo.getLocation(++lineEnd).lineNumber == lineNum);
 
   var text = content.substring(start, end);
   var lineText = content.substring(lineStart, lineEnd);
   return new SourceSpanWithContext(startLoc, endLoc, text, lineText);
 }
+
+bool isInlineJS(Element e) => e is FunctionElement &&
+    e.library.source.uri.toString() == 'dart:_foreign_helper' &&
+    e.name == 'JS';