RefCountedArray needs a size based constructor
https://bugs.webkit.org/show_bug.cgi?id=113277

Reviewed by Benjamin Poulain.

Simple patch to add a size based constructor for RefCountedArray
so that we can create an sharable array without a copy.

* wtf/RefCountedArray.h:
(RefCountedArray):
(WTF::RefCountedArray::RefCountedArray):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146964 268f45cc-cd09-0410-ab3c-d52691b4dbfc