Remove recent changes to use temp fbo to do stencil clears.

In order to implement these stencil clears we had to use a work around where we
would bind a color buffer renderbuffer to the fbo before clearing the stencil buffer.
However this workaround seems to cause the win 7 hd2000 machines to all crash on some
memory access issue.

For now we will comment on the change and go back to the old world

BUG=skia:

Review URL: https://codereview.chromium.org/1015223002
2 files changed