dart2js cps: Add a pass for eliminating bounds checks.

pkg/compiler/lib/src/tree_ir/tree_ir_tracer.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_tracer;
 
 import 'dart:async' show EventSink;
 import '../tracer.dart';
 import 'tree_ir_nodes.dart';
 
@@ skipping 115 matching lines @@
     _addStatement(node);
     visitStatement(node.body);
   }
 
   visitFor(For node) {
     Block whileBlock = new Block();
     _addGotoStatement(whileBlock);
 
     _addBlock(whileBlock);
     _addStatement(node);
-    whileBlock.statements.add(node);

[asgerf, 2015/09/16 15:25:09]

Drive-by bugfix

     blocks.last.addEdgeTo(whileBlock);
 
     Block bodyBlock = new Block();
     Block nextBlock = new Block();
     whileBlock.addEdgeTo(bodyBlock);
     whileBlock.addEdgeTo(nextBlock);
 
     continueTargets[node.label] = bodyBlock;
     _addBlock(bodyBlock);
     visitStatement(node.body);
@@ skipping 442 matching lines @@
       String prefix = v.element == null ? 'v' : '${v.element.name}_';
       while (name == null || _usedNames.contains(name)) {
         name = "$prefix${_counter++}";
       }
       _names[v] = name;
       _usedNames.add(name);
     }
     return name;
   }
 }