cps: Use BuiltinOperator.IsNumber for 'is num'

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 '../../closure.dart' show ClosureClassElement;
 import '../../common/codegen.dart' show CodegenRegistry;
@@ skipping 849 matching lines @@
         return new js.Binary('===', args[0], args[1]);
       case BuiltinOperator.StrictNeq:
         return new js.Binary('!==', args[0], args[1]);
       case BuiltinOperator.LooseEq:
         return new js.Binary('==', args[0], args[1]);
       case BuiltinOperator.LooseNeq:
         return new js.Binary('!=', args[0], args[1]);
       case BuiltinOperator.IsFalsy:
         return new js.Prefix('!', args[0]);
       case BuiltinOperator.IsNumber:
-        return js.js("typeof # === 'number'", args);
+        return js.js('typeof # === "number"', args);
       case BuiltinOperator.IsNotNumber:
-        return js.js("typeof # !== 'number'", args);
+        return js.js('typeof # !== "number"', args);
       case BuiltinOperator.IsFloor:
-        return js.js("Math.floor(#) === #", args);
+        return js.js('Math.floor(#) === #', args);
       case BuiltinOperator.IsNumberAndFloor:
-        return js.js("typeof # === 'number' && Math.floor(#) === #", args);
+        return js.js('typeof # === "number" && Math.floor(#) === #', args);
     }
   }
 
   /// The JS name of a built-in method.
   static final Map<BuiltinMethod, String> builtinMethodName = 
     const <BuiltinMethod, String>{
       BuiltinMethod.Push: 'push',
       BuiltinMethod.Pop: 'pop',
   };
 
   @override
   js.Expression visitApplyBuiltinMethod(tree_ir.ApplyBuiltinMethod node) {
     String name = builtinMethodName[node.method];
     js.Expression receiver = visitExpression(node.receiver);
     List<js.Expression> args = visitExpressionList(node.arguments);
     return js.js('#.#(#)', [receiver, name, args]);
   }
 
   @override
   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';
   }
 }