Unreviewed, rolling out r108453.

Unreviewed, rolling out r108453.
http://trac.webkit.org/changeset/108453
https://bugs.webkit.org/show_bug.cgi?id=78549

Broke Chromium's webkit_unit_tests.

Source/WebCore:

* WebCore.gypi:
* platform/graphics/chromium/cc/CCOcclusionTracker.cpp: Removed.
* platform/graphics/chromium/cc/CCOcclusionTracker.h: Removed.

Source/WebKit/chromium:

* WebKit.gypi:
* tests/CCLayerTreeHostCommonTest.cpp:
(WebCore::TEST):
(WebCore):
* tests/CCOcclusionTrackerTest.cpp: Removed.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@108467 268f45cc-cd09-0410-ab3c-d52691b4dbfc