dart2js: Use an abstract Name class for names in the generated JavaScript ast.

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 99 matching lines @@
   FUNCTION_TYPE_REQUIRED_PARAMETERS_TAG,
   /// Name used to tag optional parameters in function type representations
   /// in JavaScript.
   FUNCTION_TYPE_OPTIONAL_PARAMETERS_TAG,
   /// Name used to tag named parameters in function type representations in
   /// JavaScript.
   FUNCTION_TYPE_NAMED_PARAMETERS_TAG,
   /// Field name used for determining if an object or its interceptor has
   /// JavaScript indexing behavior.
   IS_INDEXABLE_FIELD_NAME,
+  /// String representation of the type of the null class.
+  NULL_CLASS_TYPE_NAME,
+  /// String representation of the type of the object class.
+  OBJECT_CLASS_TYPE_NAME,
+  /// String representation of the type of the function class.
+  FUNCTION_CLASS_TYPE_NAME,
 }
 
 enum JsBuiltin {
   /// Returns the JavaScript constructor function for Dart's Object class.
   /// This can be used for type tests, as in
   ///
   ///     var constructor = JS_BUILTIN('', JsBuiltin.dartObjectContructor);
   ///     if (JS('bool', '# instanceof #', obj, constructor))
   ///       ...
   dartObjectConstructor,
@@ skipping 35 matching lines @@
   ///
   /// The argument `other` is the name of the potential supertype. It is
   /// computed by `runtimeTypeToString`;
   ///
   /// *The `other` name must be passed in before the `type`.*
   ///
   ///     JS_BUILTIN('returns:bool;effects:none;depends:none',
   ///                JsBuiltin.isSubtype, other, type);
   isSubtype,
 
-  /// Returns true if the given type is _the_ `Function` type.
-  /// That is, it returns true if the given [type] is exactly the `Function`
-  /// type rti-encoding.
+  /// Returns true if the given type equals the type given as second
+  /// argument. Use the JS_GET_NAME helpers to get the type representation
+  /// for various Dart classes.
   ///
   ///     JS_BUILTIN('returns:bool;effects:none;depends:none',
-  ///                JsBuiltin.isFunctionTypeLiteral, type);
-  isFunctionTypeRti,
-
-  /// Returns whether the given type is _the_ null-type..
-  ///
-  ///     JS_BUILTIN('returns:bool;effects:none;depends:none',
-  ///                JsBuiltin.isNullType, type);
-  isNullTypeRti,
-
-  /// Returns whether the given type is _the_ Dart Object type.
-  ///
-  ///     JS_BUILTIN('returns:bool;effects:none;depends:none',
-  ///                JsBuiltin.isDartObjectType, type);
-  isDartObjectTypeRti,
+  ///                JsBuiltin.isFunctionTypeLiteral, type, name);
+  isGivenTypeRti,
 
   /// Returns the metadata of the given [index].
   ///
   ///     JS_BUILTIN('returns:var;effects:none;depends:none',
   ///                JsBuiltin.getMetadata, index);
   getMetadata,
 
   /// Returns the type of the given [index].
   ///
   ///     JS_BUILTIN('returns:var;effects:none;depends:none',
   ///                JsBuiltin.getType, index);
   getType,
 }