Un-deprecate XMLHttpRequest.send(ArrayBuffer)

Using an ArrayBuffer as the argument of send was un-deprecated in the
latest WHATWG specification, according to
https://www.w3.org/Bugs/Public/show_bug.cgi?id=26153#c1

BUG=237493

Review URL: https://codereview.chromium.org/373023002

git-svn-id: svn://svn.chromium.org/blink/trunk@178249 bbb929c8-8fbe-4397-9dbb-9b2b20218538