DelayNode doesn't work if delayTime.value == delayTime.maxValue

DelayNode doesn't work if delayTime.value == delayTime.maxValue
https://bugs.webkit.org/show_bug.cgi?id=90357

Patch by Raymond Toy <rtoy@google.com> on 2012-07-13
Reviewed by Kenneth Russell.

Source/WebCore:

Increase delay buffer size slightly so that the read and write
pointers don't become equal when the delay and the max delay are
the same.

Tests: webaudio/delaynode-max-default-delay.html
       webaudio/delaynode-max-nondefault-delay.html

* Modules/webaudio/DelayDSPKernel.cpp:
(WebCore): Moved SmoothingTimeConstant to WebCore namespace.
(WebCore::DelayDSPKernel::DelayDSPKernel): Add some additional checks to prevent crashes; use bufferLengthForDelay to compute buffer length.
(WebCore::DelayDSPKernel::bufferLengthForDelay): New function to compute buffer length.
* Modules/webaudio/DelayDSPKernel.h:
(DelayDSPKernel): Declare bufferLengthForDelay.

LayoutTests:

New tests to test the case when the delay node delay equals the
maximum allowed delay. Add one test for the default maximum delay
and a second test with a user-set maximum delay.

* webaudio/delaynode-max-default-delay-expected.txt: Added.
* webaudio/delaynode-max-default-delay.html: Added.
* webaudio/delaynode-max-nondefault-delay-expected.txt: Added.
* webaudio/delaynode-max-nondefault-delay.html: Added.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@122630 268f45cc-cd09-0410-ab3c-d52691b4dbfc