dart2js cps: More aggressive operator specialization.

pkg/compiler/lib/src/tree_ir/optimization/statement_rewriter.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.
 
 library tree_ir.optimization.statement_rewriter;
 
 import 'optimization.dart' show Pass;
 import '../tree_ir_nodes.dart';
 import '../../io/source_information.dart';
 import '../../elements/elements.dart';
@@ skipping 1243 matching lines @@
   }
 
   @override
   Statement visitYield(Yield node) {
     node.next = visitStatement(node.next);
     node.input = visitExpression(node.input);
     return node;
   }
 
   @override
-  Statement visitNullCheck(NullCheck node) {
+  Statement visitReceiverCheck(ReceiverCheck node) {
     inEmptyEnvironment(() {
       node.next = visitStatement(node.next);
     });
     if (node.condition != null) {
       inEmptyEnvironment(() {
         // Value occurs in conditional context.
         node.value = visitExpression(node.value);
       });
       node.condition = visitExpression(node.condition);
     } else {
@@ skipping 106 matching lines @@
 }
 
 /// Decrement the reference count for [e] if it is a variable use.
 void destroyPrimaryExpression(Expression e) {
   if (e is VariableUse) {
     --e.variable.readCount;
   } else {
     assert(e is This);
   }
 }