don't run dart gen on JS patch code

test/codegen_test.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.
 
 /// Tests code generation.
 /// Runs Dart Dev Compiler on all input in the `codegen` directory and checks
 /// that the output is what we expected.
 library ddc.test.codegen_test;
 
 import 'dart:io';
@@ skipping 101 matching lines @@
       // Get the test SDK. We use a checked in copy so test expectations can be
       // generated against a specific SDK version.
       // TODO(jmesserly): eventually we should track compiler messages.
       // For now we're just trying to get decent code generation.
       var options = new CompilerOptions(
           outputDir: actualDir,
           checkSdk: true,
           forceCompile: true,
           outputDart: dartGen,
           formatOutput: dartGen);
-      var sdkPath = path.join(testDir, 'generated_sdk');
+      var sdkPath = dartGen
+          ? path.join(testDir, '..', 'tool', 'input_sdk_src')
+          : path.join(testDir, 'generated_sdk');
       var testSdk = new TypeResolver.fromDir(sdkPath, options);
       var result = compile('dart:core', testSdk, options);
       var outputDir = new Directory(path.join(actualDir, 'core'));
       expect(outputDir.existsSync(), true,
           reason: '${outputDir.path} was created for dart:core');
     });
   });
 
   if (!dartGen) {
     test('devc jscodegen html_input.html', () {
@@ skipping 20 matching lines @@
     print('[AnalysisEngine] error $message $exception');
   }
 
   @override void logError2(String message, Object exception) {
     print('[AnalysisEngine] error $message $exception');
   }
 
   void logInformation(String message, [CaughtException exception]) {}
   void logInformation2(String message, Object exception) {}
 }