Fix threading races on WebAudioSourceProviderImpl::provideInput

Fix threading races on WebAudioSourceProviderImpl::provideInput 

According to the crash report (https://cluster-fuzz.appspot.com/testcase?key=4697390229487616), 
there is a threading race. Specifically, WebAudioSourceProviderImpl can be destructed by the main thread while WebAudioSourceProviderImpl::Stop() is being called by the audio thread. 

The core problem is that we're not calling WebAudioSourceProviderImpl::setClient(NULL) when HTMLMediaElement clears the audio source provider. 

BUG=284786
No tests because the crash depends on threading races and thus not reproducible.

Review URL: https://chromiumcodereview.appspot.com/23969007

git-svn-id: svn://svn.chromium.org/blink/trunk@157259 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Temporarily retrieve results from a duplicated layout-test-results dir

in garden-o-matic, the flakiness dashboard, and webkitpy.

TBR=ojan@chromium.org, abarth@chromium.org
BUG=261719

Review URL: https://codereview.chromium.org/23978004

git-svn-id: svn://svn.chromium.org/blink/trunk@157260 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Remove a deprecated method from WebCrypto.

Review URL: https://chromiumcodereview.appspot.com/23672024

git-svn-id: svn://svn.chromium.org/blink/trunk@157261 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add testing for overlay scrollbars.

The code for painting the scrollbars and computing their
size isn't used when compositing, but we still get some
testing out of the track size and computing LTR/RTL.

The RTL detection is currently broken as seen by the
RTL scrollbar showing up on the left edge.  I'll fix that
in a follow up.

BUG=None

Review URL: https://chromiumcodereview.appspot.com/23969003

git-svn-id: svn://svn.chromium.org/blink/trunk@157262 bbb929c8-8fbe-4397-9dbb-9b2b20218538
In the css3-text spec:

The start and end edges of a line box are determined by the inline base
direction of the line box. In most cases, this is given by its
containing block's computed ‘direction’. However if its containing block
has ‘unicode-bidi: plaintext’, the inline base direction the line box must
be determined by the base direction of the bidi paragraph to which it
belongs: that is, the bidi paragraph for which the line box holds content.

This patch just implements the behavior described above modifying
updateLogicalWidthForAlignment and setting the bidi level of the
RootInlineBox.

Additionally, modify two layout tests to make it conforming to the spec.

BUG=280709

Review URL: https://chromiumcodereview.appspot.com/23567004

git-svn-id: svn://svn.chromium.org/blink/trunk@157263 bbb929c8-8fbe-4397-9dbb-9b2b20218538