Update webaudio tests not to use the legacy methods.

createGainNode -> createGain
createDelayNode -> createDelay
createJavaScriptNode -> createScriptProcessor
noteOn -> start
noteGrainOn -> start
noteOff -> stop

Rename files javascriptaudionode* to scriptprocessornode*

Remove the tests for noteOn, noteGrainOn, and noteOff.

BUG=

Review URL: https://codereview.chromium.org/164473002

git-svn-id: svn://svn.chromium.org/blink/trunk@167221 bbb929c8-8fbe-4397-9dbb-9b2b20218538