fix #626, add AMD module format and make it default

test/codegen_test.dart

 // Copyright (c) 2016, 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;
 
@@ skipping 113 matching lines @@
       _collectTransitiveImports(contents, files, from: testFile);
       var unit = new BuildUnit(
           name, path.dirname(testFile), files.toList(), _moduleForLibrary);
       var module = compiler.compile(unit, options);
       _writeModule(path.join(codegenOutputDir, name),
           isTopLevelTest ? path.join(codegenExpectDir, name) : null, module);
     });
   }
 
   if (filePattern.hasMatch('sunflower')) {
-    _buildSunflower(compiler, codegenOutputDir, codegenExpectDir);
+    test('sunflower', () {
+      _buildSunflower(compiler, codegenOutputDir, codegenExpectDir);
+    });
   }
 
   if (codeCoverage) {
     test('build_sdk code coverage', () {
       return build_sdk.main(['--dart-sdk', sdkDir, '-o', codegenOutputDir]);
     });
   }
 }
 
 void _writeModule(String outPath, String expectPath, JSModuleFile result) {
@@ skipping 197 matching lines @@
 /// Simplified from ParseDartTask.resolveDirective.
 String _resolveDirective(UriBasedDirective directive) {
   StringLiteral uriLiteral = directive.uri;
   String uriContent = uriLiteral.stringValue;
   if (uriContent != null) {
     uriContent = uriContent.trim();
     directive.uriContent = uriContent;
   }
   return directive.validate() == null ? uriContent : null;
 }