Revert 88547 - Initialize RenderWidget's compositing_surface_ to NULL.  (ARM bustage)
Revert 88547 - Initialize RenderWidget's compositing_surface_ to NULL.  (ARM bustage)

BUG=80703
TEST=run the "canvas-popup.html" test case in the bug.  check the chrome_debug.log to see that no EGL or X errors are present.
Review URL: http://codereview.chromium.org/7108042

TBR=senorblanco@chromium.org
Review URL: http://codereview.chromium.org/7003092

git-svn-id: de016e52bd170d2d4f2344f9bf92d50478b649e0@88549 0039d316-1c4b-4281-b951-d872f2087c98

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