Removing empty function definitions and WebAXObject interfaces

There were *FIXME* in thirdparty/Webkit//Source/core/accessibility/AXObjectCache.cpp rregarding no necessity of the functions startCachingComputedObjectAttributesUntilTreeMutates() and stopCachingComputedObjectAttributes() and concerned WebAXObject interfaces. 

Already uploaded the patch with Chromium side changes.
(https://codereview.chromium.org/245053004/)

Review URL: https://codereview.chromium.org/242513009

git-svn-id: svn://svn.chromium.org/blink/trunk@172319 bbb929c8-8fbe-4397-9dbb-9b2b20218538
[WebSocket] Clean up stale comments about subprotocol

Also rename subprotocol related methods to include "subprotocol" in
their names.

1st comment about valid characters:
We should update "Hybi-10" to RFC6455. But instead I've made the code
self descriptive.

2nd comment about valid characters:
The disagreement has been resolved. Now the WebSocket API spec refers
to the definition of the valid characters for the Sec-WebSocket-Protocol
header in RFC6455.

Didn't replace occurrences of protocol in each method since it's clear
they mean subprotocol in those scope.

BUG=none

Review URL: https://codereview.chromium.org/246743002

git-svn-id: svn://svn.chromium.org/blink/trunk@172320 bbb929c8-8fbe-4397-9dbb-9b2b20218538
Add core Blink build configuration and WTF target to GN build.

I merged Source/config.gypi and Source/build/features.gypi into one file Source/config.gni. It wasn't clear what benefit having these separate is, and why features is in build but config is in the root dir.

Removed some unneeded warning disabling from GYP build (unknown pragmas). Remove obsolete comment about goma and clang plugins from GYP build.

I set up most of the feature defines required by WTF, with the exceptions noted with TODO(GYP).

I moved WTF_USE_DYNAMIC_ANNOTATIONS into the blink build file rather than the main build features config. This is not used outside the blink build and the reasons for it being in common.gypi don't apply to GN.

This patch will require a Chrome-side change to actually hook it up. Until that hookup happens, this code is entirely unused.

BUG=

Review URL: https://codereview.chromium.org/244753005

git-svn-id: svn://svn.chromium.org/blink/trunk@172321 bbb929c8-8fbe-4397-9dbb-9b2b20218538