dart2js: Pass type information to constructor rather than add later.

pkg/compiler/lib/src/js_emitter/startup_emitter/fragment_emitter.dart

 // Copyright (c) 2015, 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.
 
 part of dart2js.js_emitter.startup_emitter.model_emitter;
 
 /// The name of the property that stores the tear-off getter on a static
 /// function.
 ///
 /// This property is only used when isolates are used.
@@ skipping 611 matching lines @@
     });
     jsMethods[method.name] = method.code;
 
     return jsMethods;
   }
 
   /// Emits a constructor for the given class [cls].
   ///
   /// The constructor is statically built.
   js.Expression emitConstructor(Class cls) {
-    List<js.Name> fieldNames = const <js.Name>[];
-
+    js.Name name = cls.name;
     // If the class is not directly instantiated we only need it for inheritance
     // or RTI. In either case we don't need its fields.
-    if (cls.isDirectlyInstantiated && !cls.isNative) {
-      fieldNames = cls.fields.map((Field field) => field.name).toList();
+    if (cls.isNative || !cls.isDirectlyInstantiated) {
+      return js.js('function #() { }', name);
     }
-    js.Name name = cls.name;
+
+    List<js.Name> fieldNames =
+        cls.fields.map((Field field) => field.name).toList();
+    if (cls.hasRtiField) {
+      fieldNames.add(namer.rtiFieldName);
+    }
 
     Iterable<js.Name> assignments = fieldNames.map((js.Name field) {
       return js.js("this.#field = #field", {"field": field});
     });
 
+    // TODO(sra): Cache 'this' in a one-character local for 4 or more uses of
+    // 'this'. i.e. "var _=this;_.a=a;_.b=b;..."
+
+    // TODO(sra): Separate field and field initializer parameter names so the
+    // latter may be fully minified.
+
     return js.js('function #(#) { # }', [name, fieldNames, assignments]);
   }
 
   /// Emits the prototype-section of the fragment.
   ///
   /// This section updates the prototype-property of all constructors in the
   /// global holders.
   js.Statement emitPrototypes(Fragment fragment) {
     List<js.Statement> assignments = fragment.libraries
         .expand((Library library) => library.classes)
@@ skipping 694 matching lines @@
     }
     statements.add(js.js.statement("setOrUpdateInterceptorsByTag(#);",
         js.objectLiteral(interceptorsByTag)));
     statements.add(
         js.js.statement("setOrUpdateLeafTags(#);", js.objectLiteral(leafTags)));
     statements.add(subclassAssignment);
 
     return new js.Block(statements);
   }
 }