dart2js: add type lookup in the new emitter.

sdk/lib/_internal/compiler/js_lib/shared/embedded_names.dart

 // Copyright (c) 2014, 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.
 
 /// Contains the names of globals that are embedded into the output by the
 /// compiler.
 ///
 /// Variables embedded this way should be access with `JS_EMBEDDED_GLOBAL` from
 /// the `_foreign_helper` library.
 ///
@@ skipping 32 matching lines @@
 const DEFERRED_INITIALIZED = 'deferredInitialized';
 const CLASS_ID_EXTRACTOR = 'classIdExtractor';
 const CLASS_FIELDS_EXTRACTOR = 'classFieldsExtractor';
 const INSTANCE_FROM_CLASS_ID = "instanceFromClassId";
 const INITIALIZE_EMPTY_INSTANCE = "initializeEmptyInstance";
 const TYPEDEF_TYPE_PROPERTY_NAME = r"$typedefType";
 const TYPEDEF_PREDICATE_PROPERTY_NAME = r"$$isTypedef";
 const NATIVE_SUPERCLASS_TAG_NAME = r"$nativeSuperclassTag";
 
 const MAP_TYPE_TO_INTERCEPTOR = "mapTypeToInterceptor";
+
+/**
+ * Returns the type given the name of a class.
+ * This function is called by the runtime when computing rti.
+ */
+const GET_TYPE_FROM_NAME = 'getTypeFromName';