[asm] Fix lots of invalid asm.js tests

test/mjsunit/asm/zero-extend.js

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 var stdlib = this;
 var buffer = new ArrayBuffer(64 * 1024);
 var foreign = {}
 
 
 var zext8 = (function Module(stdlib, foreign, heap) {
   "use asm";
   function zext8(i) {
-    i = i|0;
-    return i & 0xff;
+    i = i | 0;
+    return (i & 0xff) | 0;
   }
   return { zext8: zext8 };
 })(stdlib, foreign, buffer).zext8;
 
 assertEquals(0, zext8(0));
 assertEquals(0, zext8(0x100));
 assertEquals(0xff, zext8(-1));
 assertEquals(0xff, zext8(0xff));
 
 
 var zext16 = (function Module(stdlib, foreign, heap) {
   "use asm";
   function zext16(i) {
-    i = i|0;
-    return i & 0xffff;
+    i = i | 0;
+    return (i & 0xffff) | 0;
   }
   return { zext16: zext16 };
 })(stdlib, foreign, buffer).zext16;
 
 assertEquals(0, zext16(0));
 assertEquals(0, zext16(0x10000));
 assertEquals(0xffff, zext16(-1));
 assertEquals(0xffff, zext16(0xffff));