Initialize page visibility after creating WebKitTestRunner WebView on Mac
https://bugs.webkit.org/show_bug.cgi?id=111025

Patch by Kiran Muppala <cmuppala@apple.com> on 2013-02-27
Reviewed by Simon Fraser.

Set page visibility to "visible" after creating WebView to override
visibility state inferred from window occlusion notifications on Mac.

* WebKitTestRunner/TestController.cpp:
(WTR::TestController::createWebViewWithOptions): Add call to
setVisibilityState.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@144259 268f45cc-cd09-0410-ab3c-d52691b4dbfc