dart2js cps: Introduce '<<' operator in type propagation.

pkg/compiler/lib/src/js_backend/codegen/codegen.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 code_generator;
 
 import 'glue.dart';
 
 import '../../tree_ir/tree_ir_nodes.dart' as tree_ir;
 import '../../tree_ir/tree_ir_nodes.dart' show BuiltinOperator;
@@ skipping 782 matching lines @@
       case BuiltinOperator.NumXor:
         return js.js('(# ^ #) >>> 0', args);
       case BuiltinOperator.NumLt:
         return new js.Binary('<', args[0], args[1]);
       case BuiltinOperator.NumLe:
         return new js.Binary('<=', args[0], args[1]);
       case BuiltinOperator.NumGt:
         return new js.Binary('>', args[0], args[1]);
       case BuiltinOperator.NumGe:
         return new js.Binary('>=', args[0], args[1]);
+      case BuiltinOperator.NumShl:
+        return js.js('(# << #) >>> 0', args);
       case BuiltinOperator.StringConcatenate:
         if (args.isEmpty) return js.string('');
         return args.reduce((e1,e2) => new js.Binary('+', e1, e2));
       case BuiltinOperator.Identical:
         registry.registerStaticInvocation(glue.identicalFunction);
         return buildStaticHelperInvocation(glue.identicalFunction, args);
       case BuiltinOperator.StrictEq:
         return new js.Binary('===', args[0], args[1]);
       case BuiltinOperator.StrictNeq:
         return new js.Binary('!==', args[0], args[1]);
@@ skipping 18 matching lines @@
   js.Expression visitAwait(tree_ir.Await node) {
     return new js.Await(visitExpression(node.input));
   }
 
   visitFunctionExpression(tree_ir.FunctionExpression node) {
     // FunctionExpressions are currently unused.
     // We might need them if we want to emit raw JS nested functions.
     throw 'FunctionExpressions should not be used';
   }
 }