Add flag to disable hashing

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 dev_compiler.test.codegen_test;
 
 import 'dart:io';
@@ skipping 62 matching lines @@
         useColors: false,
         outputDart: dartGen,
         formatOutput: dartGen,
         emitSourceMaps: sourceMaps,
         forceCompile: checkSdk,
         cheapTestFormat: checkSdk,
         checkSdk: checkSdk,
         entryPointFile: entryPoint,
         dartSdkPath: sdkPath,
         runtimeDir: runtimeDir,
-        serverMode: serverMode);
+        serverMode: serverMode,
+        enableHashing: serverMode);
     return new Compiler(options).run();
   }
   var realSdk = getSdkDir(arguments).path;
 
   // Remove old output, and `packages` symlinks which mess up the diff.
   var dir = new Directory(actualDir);
   if (dir.existsSync()) dir.deleteSync(recursive: true);
   var packagesDirs = new Directory(inputDir)
       .listSync(recursive: true)
       .where((d) => d is Directory && path.basename(d.path) == 'packages');
@@ skipping 187 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) {}
 }