dart2js: add mangled-global-names embedded global to 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.
 ///
 /// This library is shared between the compiler and the runtime system.
 library dart2js._embedded_names;
 
 const DISPATCH_PROPERTY_NAME = "dispatchPropertyName";
 const TYPE_INFORMATION = 'typeInformation';
 const GLOBAL_FUNCTIONS = 'globalFunctions';
 const STATICS = 'statics';
 
-/**
- * If [JSInvocationMirror._invokeOn] is being used, this embedded global
- * contains a JavaScript map with the names of methods that are
- * intercepted.
- */
+/// If [JSInvocationMirror._invokeOn] is being used, this embedded global
+/// contains a JavaScript map with the names of methods that are
+/// intercepted.
 const INTERCEPTED_NAMES = 'interceptedNames';
 
+/// A JS map from mangled global names to their unmangled names.
+///
+/// If the program does not use reflection may be empty (but not null or
+/// undefined).
 const MANGLED_GLOBAL_NAMES = 'mangledGlobalNames';
+
 const MANGLED_NAMES = 'mangledNames';
 const LIBRARIES = 'libraries';
 const FINISHED_CLASSES = 'finishedClasses';
 const ALL_CLASSES = 'allClasses';
 const METADATA = 'metadata';
 const INTERCEPTORS_BY_TAG = 'interceptorsByTag';
 const LEAF_TAGS = 'leafTags';
 const LAZIES = 'lazies';
 const GET_ISOLATE_TAG = 'getIsolateTag';
 const ISOLATE_TAG = 'isolateTag';
 const CURRENT_SCRIPT = 'currentScript';
 const DEFERRED_LIBRARY_URIS = 'deferredLibraryUris';
 const DEFERRED_LIBRARY_HASHES = 'deferredLibraryHashes';
 const INITIALIZE_LOADED_HUNK = 'initializeLoadedHunk';
 const IS_HUNK_LOADED = 'isHunkLoaded';
 const IS_HUNK_INITIALIZED = 'isHunkInitialized';
 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";
 
-/**
- * Returns the type given the name of a class.
- * This function is called by the runtime when computing rti.
- */
+/// 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';
 const TYPE_TO_INTERCEPTOR_MAP = "typeToInterceptorMap";