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
Auto-rebaseline for r173730

http://src.chromium.org/viewvc/blink?view=revision&revision=173730

BUG=25293
TBR=sudarshan.p@samsung.com

Review URL: https://codereview.chromium.org/274053002

git-svn-id: svn://svn.chromium.org/blink/trunk@173738 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Auto-rebaseline for r173722

http://src.chromium.org/viewvc/blink?view=revision&revision=173722

BUG=371698
TBR=dominicc@chromium.org

Review URL: https://codereview.chromium.org/278833002

git-svn-id: svn://svn.chromium.org/blink/trunk@173739 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Gardening: http/tests/webfont/slow-loading.html is flaky

BUG=371725
TBR=ksakamoto

Review URL: https://codereview.chromium.org/275813002

git-svn-id: svn://svn.chromium.org/blink/trunk@173740 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Compute distinguishing argument index

The "distinguishing argument index" is the next part of the overload
resolution algorithm.

In overload resolution, you first distinguish by number of arguments,
then distinguish by checking the type of a single argument at some index;
this CL adds the index computation.

In practice it's just the first index where types differ,
but there are additional conditions to check.
http://heycam.github.io/webidl/#dfn-distinguishing-argument-index

Next CL will add the very lengthy "distinguishability classes".

After that we'll finally be ready to start changing the code generation,
based first on number of arguments, secondly on type!

Also:
* Some refactoring
* Fixes some tests that were invalid overloads, and were caught
by the new checks!
(No invalid overloads in actual IDLs, but test cases were too simple.)

R=haraken
BUG=293561

Review URL: https://codereview.chromium.org/275763002

git-svn-id: svn://svn.chromium.org/blink/trunk@173741 bbb929c8-8fbe-4397-9dbb-9b2b20218538