[GTK] Enable Web Audio layout tests on WK2, provide platform-specific expected output
https://bugs.webkit.org/show_bug.cgi?id=114513

Reviewed by Philippe Normand.

Unskip the Web Audio layout tests for GTK WK2 and generate platform-specific baselines for the tests.
The audio baselines are not audibly different from the generic baselines, but it can be expected that
different backends won't produce the same binary output.

The remaining failures are marked as such in the TestExpectations, each failure having the appropriate
bug handle covering the issue. The tests are still skipped for GTK WK1 as DumpRenderTree is still missing
infrastructure support for running these tests.

* platform/gtk-wk1/TestExpectations:
* platform/gtk/TestExpectations:
* platform/gtk/webaudio/audiobuffersource-loop-points-expected.wav: Added.
* platform/gtk/webaudio/audiobuffersource-playbackrate-expected.wav: Added.
* platform/gtk/webaudio/codec-tests/aac/vbr-128kbps-44khz-expected.wav: Added.
* platform/gtk/webaudio/codec-tests/mp3/128kbps-44khz-expected.wav: Added.
* platform/gtk/webaudio/codec-tests/vorbis/vbr-128kbps-44khz-expected.wav: Added.
* platform/gtk/webaudio/codec-tests/vorbis/vbr-70kbps-44khz-expected.wav: Added.
* platform/gtk/webaudio/codec-tests/vorbis/vbr-96kbps-44khz-expected.wav: Added.
* platform/gtk/webaudio/codec-tests/wav/24bit-22khz-resample-expected.wav: Added.
* platform/gtk/webaudio/codec-tests/wav/24bit-44khz-expected.wav: Added.
* platform/gtk/webaudio/oscillator-custom-expected.wav: Added.
* platform/gtk/webaudio/oscillator-sawtooth-expected.wav: Added.
* platform/gtk/webaudio/oscillator-sine-expected.wav: Added.
* platform/gtk/webaudio/oscillator-square-expected.wav: Added.
* platform/gtk/webaudio/oscillator-triangle-expected.wav: Added.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@149181 268f45cc-cd09-0410-ab3c-d52691b4dbfc