[regexp] Remove unused InternalPackedArray

Review-Url: https://codereview.chromium.org/2397373004
Cr-Commit-Position: refs/heads/master@{#40130}

src/js/regexp.js

@@ -16,7 +16,6 @@ var GlobalObject = global.Object;
 var GlobalRegExp = global.RegExp;
 var GlobalRegExpPrototype = GlobalRegExp.prototype;
 var InternalArray = utils.InternalArray;
-var InternalPackedArray = utils.InternalPackedArray;
 var MaxSimple;
 var MinSimple;
 var RegExpExecJS = GlobalRegExp.prototype.exec;