Revert of Fix webkit_unit_tests to use the threaded parser and enable everywhere. (https://codereview.chromium.org/271793007/)

Reason for revert:
Sorry to revert this patch. The assert it adds is getting hit in webkit_unit_tests on WebKit Mac 10.6 (dbg).

Log: http://build.chromium.org/p/chromium.webkit/builders/WebKit%20Mac10.6%20%28dbg%29/builds/14735/steps/webkit_unit_tests/logs/stdio

Snippet from log:
ASSERTION FAILED: !testClientForFrame(m_webView->mainFrame())->isLoading()
../../third_party/WebKit/Source/web/tests/FrameTestHelpers.cpp(271) : void blink::FrameTestHelpers::WebViewHelper::reset()

Original issue's description:
> Fix webkit_unit_tests to use the threaded parser and enable everywhere.
> 
> In order to support the threaded parser, FrameTestHelpers utilities has
> been updated to magically wait for loads to finish. There are also
> several new helpers for other common operations in tests that
> understand how to wait for the threaded parser to complete.
> 
> Tests that need to interleave more complicated operations can fall back
> to pumpPendingRequestsDoNotUse(). Most tests should prefer the new
> helper utilities though.
> 
> BUG=366354
> R=abarth@chromium.org, eseidel@chromium.org
> 
> Committed: https://src.chromium.org/viewvc/blink?view=rev&revision=173731

TBR=abarth@chromium.org,eseidel@chromium.org,dcheng@chromium.org
NOTREECHECKS=true
NOTRY=true
BUG=366354

Review URL: https://codereview.chromium.org/272143002

git-svn-id: svn://svn.chromium.org/blink/trunk@173737 bbb929c8-8fbe-4397-9dbb-9b2b20218538