Move allocation profiler out of experiment

It is replaced with a checkbox on the Settings panel called "Record heap allocation stack traces". When that checkbox is ticked "Record heap allocations" profile will also record allocation stack traces.

BUG=277984

Review URL: https://codereview.chromium.org/348893005

git-svn-id: svn://svn.chromium.org/blink/trunk@176974 bbb929c8-8fbe-4397-9dbb-9b2b20218538
WebAudio: Add factory functions to AudioNodeInput and AudioNodeOutput.

Also, AudioNode::addInput is used with a fixed argument. This CL fold the
argument into addInput implementation.

BUG=
TEST=none; no behavior changes.

Review URL: https://codereview.chromium.org/356833004

git-svn-id: svn://svn.chromium.org/blink/trunk@176975 bbb929c8-8fbe-4397-9dbb-9b2b20218538