Implement MediaElementAudioSourceNode::setFormat() so numberOfChannels and sampleRate are accounted for

      https://bugs.webkit.org/show_bug.cgi?id=75057

Reviewed by Eric Carlson.

* GNUmakefile.list.am:
* WebCore.gypi:
* WebCore.xcodeproj/project.pbxproj:
Add MultiChannelResampler source files to makefiles.
* platform/audio/MultiChannelResampler.cpp: Added.
(WebCore::MultiChannelResampler::MultiChannelResampler):
(WebCore::MultiChannelResampler::process):
* platform/audio/MultiChannelResampler.h: Added.
Add MultiChannelResampler implementation which uses one SincResampler per channel.
* webaudio/MediaElementAudioSourceNode.cpp:
(WebCore::MediaElementAudioSourceNode::create):
(WebCore::MediaElementAudioSourceNode::MediaElementAudioSourceNode):
(WebCore::MediaElementAudioSourceNode::setFormat):
(WebCore::MediaElementAudioSourceNode::process):
Implement MediaElementAudioSourceNode::setFormat() so that we can
properly setup a sample-rate converter and set the number of channels
of the MediaElementAudioSourceNode output.
* webaudio/MediaElementAudioSourceNode.h:

git-svn-id: svn://svn.chromium.org/blink/trunk@103581 bbb929c8-8fbe-4397-9dbb-9b2b20218538