Revert 176298 "[WebSocket] bufferedAmount should not decrease in..."

This CL broke browser_tests (WebSocket2):
http://build.chromium.org/p/chromium.webkit/builders/Mac10.8%20Tests/builds/8151

> [WebSocket] bufferedAmount should not decrease inside a task.
> 
> The spec says that bufferedAmount must not decrease in the task that
> send() is called.
> Fixed both the new and the old implementation although the old implementaion
> is at any rate broken (bufferedAmount in the old implementation includes
> the protocol overhead).
> 
> BUG=159563
> 
> Review URL: https://codereview.chromium.org/311993006

TBR=yhirano@chromium.org

Review URL: https://codereview.chromium.org/338243006

git-svn-id: svn://svn.chromium.org/blink/trunk@176311 bbb929c8-8fbe-4397-9dbb-9b2b20218538