dart2js cps: Introduce some built-in operators in type propagation.

pkg/compiler/lib/src/tree_ir/optimization/pull_into_initializers.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.
 
 library tree_ir.optimization.pull_into_initializers;
 
 import 'optimization.dart' show Pass;
 import '../tree_ir_nodes.dart';
 
 /// Pulls assignment expressions to the top of the function body so they can be
@@ skipping 307 matching lines @@
   }
 
   Expression visitVariableUse(VariableUse node) {
     return node;
   }
 
   Expression visitCreateInvocationMirror(CreateInvocationMirror node) {
     rewriteList(node.arguments);
     return node;
   }
+
+  Expression visitApplyBuiltinOperator(ApplyBuiltinOperator node) {
+    rewriteList(node.arguments);
+    return node;
+  }
 }