Fix ParameterMirror.hasDefaultValue/defaultValue in source mirrors.

tests/compiler/dart2js/memory_compiler.dart

 // Copyright (c) 2013, 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 dart2js.test.memory_compiler;
 
 import 'memory_source_file_helper.dart';
 
 import '../../../sdk/lib/_internal/compiler/implementation/dart2jslib.dart'
        show NullSink;
@@ skipping 65 matching lines @@
 
 Expando<MemorySourceFileProvider> expando =
     new Expando<MemorySourceFileProvider>();
 
 Compiler compilerFor(Map<String,String> memorySourceFiles,
                      {DiagnosticHandler diagnosticHandler,
                       List<String> options: const [],
                       Compiler cachedCompiler,
                       bool showDiagnostics: true,
                       Uri packageRoot}) {
-  Uri script = currentDirectory.resolveUri(Platform.script);
-  Uri libraryRoot = script.resolve('../../../sdk/');
+  Uri libraryRoot = Uri.base.resolve('sdk/');
+  Uri script = Uri.base.resolveUri(Platform.script);
   if (packageRoot == null) {
-    packageRoot = currentDirectory.resolve(
-        appendSlash(nativeToUriPath(Platform.packageRoot)));
+    packageRoot = Uri.base.resolve('${Platform.packageRoot}/');
   }
 
   MemorySourceFileProvider provider;
   var readStringFromUri;
   if (cachedCompiler == null) {
     provider = new MemorySourceFileProvider(memorySourceFiles);
     readStringFromUri = provider.readStringFromUri;
     // Saving the provider in case we need it later for a cached compiler.
     expando[readStringFromUri] = provider;
   } else {
@@ skipping 50 matching lines @@
       }
     });
   }
   return compiler;
 }
 
 Future<MirrorSystem> mirrorSystemFor(Map<String,String> memorySourceFiles,
                                      {DiagnosticHandler diagnosticHandler,
                                       List<String> options: const [],
                                       bool showDiagnostics: true}) {
-  Uri script = currentDirectory.resolveUri(Platform.script);
-  Uri libraryRoot = script.resolve('../../../sdk/');
-  Uri packageRoot = script.resolve('./packages/');
+  Uri libraryRoot = Uri.base.resolve('sdk/');
+  Uri packageRoot = Uri.base.resolve('${Platform.packageRoot}/');
+  Uri script = Uri.base.resolveUri(Platform.script);
 
   var provider = new MemorySourceFileProvider(memorySourceFiles);
   var handler =
       createDiagnosticHandler(diagnosticHandler, provider, showDiagnostics);
 
   List<Uri> libraries = <Uri>[];
   memorySourceFiles.forEach((String path, _) {
     libraries.add(new Uri(scheme: 'memory', path: path));
   });
 
   return analyze(libraries, libraryRoot, packageRoot,
                  provider, handler, options);
 }