Implement OfflineAudioContext constructor
https://bugs.webkit.org/show_bug.cgi?id=104188

Reviewed by Kentaro Hara.

Source/WebCore:

The Web Audio layout tests have relied on an undocumented way (in the specification) to render
audio faster than realtime using an OfflineAudioContext.  We want to expose a proper OfflineAudioContext
object and constructor instead of piggybacking off of the normal AudioContext.

* CMakeLists.txt:
* DerivedSources.make:
* DerivedSources.pri:
* GNUmakefile.list.am:
* Modules/webaudio/AudioContext.cpp:
(WebCore::AudioContext::isSampleRateRangeGood):
* Modules/webaudio/AudioContext.h:
(AudioContext):
* Modules/webaudio/DOMWindowWebAudio.idl:
* Modules/webaudio/OfflineAudioContext.cpp: Added.
(WebCore):
(WebCore::OfflineAudioContext::create):
(WebCore::OfflineAudioContext::OfflineAudioContext):
(WebCore::OfflineAudioContext::~OfflineAudioContext):
* Modules/webaudio/OfflineAudioContext.h: Added.
(WebCore):
(OfflineAudioContext):
* Modules/webaudio/OfflineAudioContext.idl: Added.
* WebCore.gypi:
* WebCore.xcodeproj/project.pbxproj:
* bindings/generic/RuntimeEnabledFeatures.h:
(WebCore::RuntimeEnabledFeatures::webkitOfflineAudioContextEnabled):
* bindings/js/JSAudioContextCustom.cpp:
(WebCore::JSAudioContextConstructor::constructJSAudioContext):
* bindings/v8/custom/V8AudioContextCustom.cpp:
(WebCore::V8AudioContext::constructorCallbackCustom):

LayoutTests:

Switch Web Audio layout tests to use OfflineAudioContext constructor.

* inspector-protocol/nmi-webaudio.html:
* inspector-protocol/resources/audio-context.html:
* webaudio/audiobuffersource-loop-comprehensive.html:
* webaudio/audiobuffersource-loop-points.html:
* webaudio/audiobuffersource-multi-channels.html:
* webaudio/audiobuffersource-playbackState.html:
* webaudio/audiobuffersource-playbackrate.html:
* webaudio/audiobuffersource-start.html:
* webaudio/audiobuffersource.html:
* webaudio/audiochannelmerger-stereo.html:
* webaudio/audiochannelsplitter.html:
* webaudio/audionode-connect-order.html:
* webaudio/audionode-expected.txt:
* webaudio/audioparam-connect-audioratesignal.html:
* webaudio/audioparam-summingjunction.html:
* webaudio/automatic-pull-node.html:
* webaudio/biquad-allpass.html:
* webaudio/biquad-bandpass.html:
* webaudio/biquad-highpass.html:
* webaudio/biquad-highshelf.html:
* webaudio/biquad-lowpass.html:
* webaudio/biquad-lowshelf.html:
* webaudio/biquad-notch.html:
* webaudio/biquad-peaking.html:
* webaudio/convolution-mono-mono.html:
* webaudio/delaynode-max-default-delay.html:
* webaudio/delaynode-max-nondefault-delay.html:
* webaudio/delaynode-maxdelay.html:
* webaudio/delaynode-maxdelaylimit.html:
* webaudio/delaynode-scheduling.html:
* webaudio/delaynode.html:
* webaudio/distance-exponential.html:
* webaudio/distance-inverse.html:
* webaudio/distance-linear.html:
* webaudio/gain.html:
* webaudio/javascriptaudionode-zero-input-channels.html:
* webaudio/javascriptaudionode.html:
* webaudio/mediaelementaudiosourcenode-gc.html:
* webaudio/mixing.html:
* webaudio/note-grain-on-play.html:
* webaudio/note-grain-on-timing.html:
* webaudio/oscillator-basic.html:
* webaudio/panner-equalpower-stereo.html:
* webaudio/panner-equalpower.html:
* webaudio/realtimeanalyser-fft-sizing.html:
* webaudio/resources/audio-codec-test.js:
(runDecodingTest):
* webaudio/resources/audioparam-testing.js:
(createAudioGraphAndTest):
* webaudio/resources/javascriptaudionode-testing.js:
(runJSNodeTest):
* webaudio/sample-accurate-scheduling.html:
* webaudio/stereo2mono-down-mixing.html:
* webaudio/up-mixing-mono-51.html:
* webaudio/up-mixing-mono-stereo.html:
* webaudio/up-mixing-stereo-51.html:
* webaudio/waveshaper.html:

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@137398 268f45cc-cd09-0410-ab3c-d52691b4dbfc