Unreviewed, rolling out r149338.

Unreviewed, rolling out r149338.
http://trac.webkit.org/changeset/149338
https://bugs.webkit.org/show_bug.cgi?id=115409

Broke layout/perf/API tests on non-Mac:
ThreadSpecific<RefPtr<RunLoop>> does not initialize RunLoop
(Requested by rakuco on #webkit).

* platform/RunLoop.cpp:
(WebCore::RunLoop::current):
* platform/RunLoop.h:
(RunLoop):
* platform/cf/RunLoopCF.cpp:
(WebCore::RunLoop::initializeMainRunLoop):
(WebCore::RunLoop::current):
(WebCore::RunLoop::~RunLoop):
* platform/efl/RunLoopEfl.cpp:
(WebCore::RunLoop::~RunLoop):
* platform/gtk/RunLoopGtk.cpp:
(WebCore::RunLoop::~RunLoop):
* platform/win/RunLoopWin.cpp:
(WebCore::RunLoop::~RunLoop):

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@149358 268f45cc-cd09-0410-ab3c-d52691b4dbfc