Disable window occlusion detection for WebKitTestRunner Web View on Mac

Disable window occlusion detection for WebKitTestRunner Web View on Mac
https://bugs.webkit.org/show_bug.cgi?id=111116

Patch by Kiran Muppala <cmuppala@apple.com> on 2013-02-28
Reviewed by Simon Fraser.

Window occlusion notifications were causing WebKitTestRunner's Web View
to be detected as occluded and causing a few JavaScript timer layout
tests to fail.  https://bugs.webkit.org/show_bug.cgi?id=111025, fixed this
by initializing the page visibility to "visible" after creating the view.
But a better solution is to disable window occlusion detection, so that
not only the page but also the view is treated as visible.

* WebKitTestRunner/TestController.cpp:
(WTR::TestController::createWebViewWithOptions): Remove call to
setVisibilityState, since it is no longer necessary.
* WebKitTestRunner/mac/PlatformWebViewMac.mm:
(WTR::PlatformWebView::PlatformWebView): Disable window occlusion
detection for the created WKView.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@144415 268f45cc-cd09-0410-ab3c-d52691b4dbfc