Unreviewed, rolling out r145280.
http://trac.webkit.org/changeset/145280
https://bugs.webkit.org/show_bug.cgi?id=112217

This patch broke chromium WebGL conformance tests (Requested
by shawnsingh on #webkit).

Patch by Sheriff Bot <webkit.review.bot@gmail.com> on 2013-03-12

* platform/graphics/gpu/DrawingBuffer.cpp:
(WebCore::DrawingBuffer::reset):
* platform/graphics/gpu/DrawingBuffer.h:
(DrawingBuffer):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@145649 268f45cc-cd09-0410-ab3c-d52691b4dbfc