Correctly compile unresolved for-in loops.

dart/tests/compiler/dart2js/memory_source_file_helper.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_source_file_helper;
+
+import 'dart:async' show Future;
+import 'dart:uri' show Uri;
+export 'dart:uri' show Uri;
+import 'dart:io';
+export 'dart:io' show Options;
+
+export '../../../sdk/lib/_internal/compiler/implementation/apiimpl.dart'
+       show Compiler;
+
+export '../../../sdk/lib/_internal/compiler/implementation/filenames.dart'
+       show getCurrentDirectory, nativeToUriPath;
+
+import '../../../sdk/lib/_internal/compiler/implementation/source_file.dart'
+       show SourceFile;
+
+import '../../../sdk/lib/_internal/compiler/implementation/source_file_provider.dart'
+       show SourceFileProvider;
+
+export '../../../sdk/lib/_internal/compiler/implementation/source_file_provider.dart'
+       show FormattingDiagnosticHandler;
+
+class MemorySourceFileProvider extends SourceFileProvider {
+  static Map MEMORY_SOURCE_FILES;
+  Future<String> readStringFromUri(Uri resourceUri) {
+    if (resourceUri.scheme != 'memory') {
+      return super.readStringFromUri(resourceUri);
+    }
+    String source = MEMORY_SOURCE_FILES[resourceUri.path];
+    // TODO(ahe): Return new Future.immediateError(...) ?
+    if (source == null) throw 'No such file $resourceUri';
+    String resourceName = '$resourceUri';
+    this.sourceFiles[resourceName] = new SourceFile(resourceName, source);
+    return new Future.immediate(source);
+  }
+}