[Soup] Random thread crashes
https://bugs.webkit.org/show_bug.cgi?id=107439

Reviewed by Martin Robinson.

Process all pending requests in the inner GMainContext created to
perform synchronous requests before restoring the thread default. No
new tests required, already covered by network tests.

* platform/network/soup/ResourceHandleSoup.cpp:
(WebCore::WebCoreSynchronousLoader::~WebCoreSynchronousLoader):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@140445 268f45cc-cd09-0410-ab3c-d52691b4dbfc