JS tree shaking for incremental builds.

compiler/lib/implementation/rtt.js

 // Copyright (c) 2011, 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.
 
 // The following methods are used to handle type information
 //
 
 /** 
  * @constructor
  * @param {string} classkey
@@ skipping 190 matching lines @@
   if (!rtt) {
     throw new Error("internal error: can not find " +
         classkey + " in " + JSON.stringify(o));
   }
   return rtt.typeArgs;
 };
 
 // Base types for runtime type information
 
 /** @type {!RTT} */
-RTT.objectType = new RTT($cls('Object'));
-RTT.objectType.implementedBy = function(o) {return true};
-RTT.objectType.implementedByType = function(o) {return true};
+function ImplementsAll(name) {
+  RTT.call(this,name);
+}
+$inherits(ImplementsAll,RTT);
+ImplementsAll.prototype.implementedBy = function(o) {return true};
+ImplementsAll.prototype.implementedByType = function(o) {return true};
 
-/** @type {!RTT} */
-RTT.dynamicType = new RTT($cls('Dynamic'));
-RTT.dynamicType.implementedBy = function(o) {return true};
-RTT.dynamicType.implementedByType = function(o) {return true};
-
-/** @type {!RTT} */
-RTT.placeholderType = new RTT($cls('::'));
-RTT.placeholderType.implementedBy = function(o) {return true};
-RTT.placeholderType.implementedByType = function(o) {return true};
+RTT.objectType = new ImplementsAll($cls('Object'));
+RTT.dynamicType = new ImplementsAll($cls('Dynamic')); 
+RTT.placeholderType = new ImplementsAll($cls('::'));
 
 /**
  * Checks that a value is assignable to an expected type, and either returns that
  * value if it is, or else throws a TypeMismatchException.
  *
  * @param {!RTT} the expected type
  * @param {*} the value to check
  * @return {*} the value
  */
 function $chk(rtt, value) {
@@ skipping 46 matching lines @@
   return typeof o == 'number';
 }
 
 /**
  * @param {*} o
  * @return {boolean}
  */
 function $isString(o) {
   return typeof o == 'string';
 }