This change was causing many flakes in
webaudio/audiobuffersource-multi-channels.html and
webaudio/up-mixing-*-51.html.

Revert "Ensure that ArrayBuffers actively being used by the Web Audio API cannot be neutered"

This reverts commit fe5d3b7dc4b87a0815737dd8faff1e224205a5b1.

Conflicts:

	Source/modules/webaudio/AudioBuffer.cpp
	Source/modules/webaudio/AudioBuffer.h

git-svn-id: svn://svn.chromium.org/blink/trunk@154493 bbb929c8-8fbe-4397-9dbb-9b2b20218538