AudioNode test should cover numberOfInputs and numberOfOutputs of AudioDestinationNode

AudioNode test should cover numberOfInputs and numberOfOutputs of AudioDestinationNode
https://bugs.webkit.org/show_bug.cgi?id=90578

Patch by Li Yin <li.yin@intel.com> on 2012-07-04
Reviewed by Chris Rogers.

Spec: http://www.w3.org/TR/webaudio/#AudioDestinationNode-section
An AudioSourceNode has no inputs and a single output.
An AudioDestinationNode has one input and no outputs.
Currently, the test webaudio/audionode.html has covered AudioSourceNode,
it is still required to cover AudioDestinationNode.

* webaudio/audionode-expected.txt:
* webaudio/audionode.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@121877 268f45cc-cd09-0410-ab3c-d52691b4dbfc