Passing invalid values to OfflineAudioContext's constructor should not crash.

Passing invalid values to OfflineAudioContext's constructor should not crash.
https://bugs.webkit.org/show_bug.cgi?id=141197

Reviewed by Darin Adler.

Source/WebCore:

Test: webaudio/offlineaudiocontext-constructor.html

Throw a SYNTAX_ERR exception if passed in a zero for channelCount or numberOfSamples. This avoids
a crash where OfflineAudioDestinationNode is passed a null renderTarget.

* Modules/webaudio/OfflineAudioContext.cpp:
(WebCore::OfflineAudioContext::create):

LayoutTests:

* webaudio/offlineaudiocontext-constructor-expected.txt: Added.
* webaudio/offlineaudiocontext-constructor.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@179565 268f45cc-cd09-0410-ab3c-d52691b4dbfc