Fix some bugs regarding native fields.

dart/sdk/lib/_internal/compiler/implementation/apiimpl.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 leg_apiimpl;
 
 import 'dart:async';
 
 import '../compiler.dart' as api;
 import 'dart2jslib.dart' as leg;
@@ skipping 240 matching lines @@
 
   Uri resolvePatchUri(String dartLibraryPath) {
     String patchPath = lookupPatchPath(dartLibraryPath);
     if (patchPath == null) return null;
     return libraryRoot.resolve(patchPath);
   }
 
   Uri translatePackageUri(Uri uri, tree.Node node) {
     if (packageRoot == null) {
       if (node != null) {
-        reportErrorCode(node, 
+        reportErrorCode(node,
             leg.MessageKind.PACKAGE_ROOT_NOT_SET,
             {'uri': uri});
       } else {
-        reportDiagnostic(null, 
+        reportDiagnostic(null,
             leg.MessageKind.PACKAGE_ROOT_NOT_SET.error({'uri': uri}).toString(),
             api.Diagnostic.ERROR);
-        
       }
       throw new leg.CompilerCancelledException("Package root not set.");
     }
     return packageRoot.resolve(uri.path);
   }
 
   bool run(Uri uri) {
     log('Allowed library categories: $allowedLibraryCategories');
     bool success = super.run(uri);
     int cumulated = 0;
@@ skipping 21 matching lines @@
       handler(translateUri(span.uri, null), span.begin, span.end,
               message, kind);
     }
   }
 
   bool get isMockCompilation {
     return mockableLibraryUsed
       && (options.indexOf('--allow-mock-compilation') != -1);
   }
 }