dart2js cps: Add instruction for bounds checks.

pkg/compiler/lib/src/tree_ir/tree_ir_builder.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_builder;
 
 import '../common.dart';
 import '../constants/values.dart';
 import '../cps_ir/cps_ir_nodes.dart' as cps_ir;
 import '../elements/elements.dart';
@@ skipping 659 matching lines @@
   @override
   Expression visitAwait(cps_ir.Await node) {
     return new Await(getVariableUse(node.input));
   }
 
   @override
   Expression visitRefinement(cps_ir.Refinement node) {
     throw 'Unexpected Refinement node in tree builder';
   }
 
+  @override
+  Expression visitBoundsCheck(cps_ir.BoundsCheck node) {
+    throw 'Unexpected BoundsCheck node in tree builder';
+  }
+
   /********** UNUSED VISIT METHODS *************/
 
   unexpectedNode(cps_ir.Node node) {
     internalError(CURRENT_ELEMENT_SPANNABLE, 'Unexpected IR node: $node');
   }
 
   visitFunctionDefinition(cps_ir.FunctionDefinition node) {
     unexpectedNode(node);
   }
   visitParameter(cps_ir.Parameter node) => unexpectedNode(node);
@@ skipping 18 matching lines @@
     --enclosingFunctions;
   }
 
   @override
   visitInterpolatedNode(js.InterpolatedNode node) {
     if (enclosingFunctions > 0) {
       found = true;
     }
   }
 }