Add methods to compute magnitude and phase response for biquads

   Add methods to compute magnitude and phase response for biquads
       https://bugs.webkit.org/show_bug.cgi?id=71055

       Reviewed by Kenneth Russell.

Patch by Raymond Toy <rtoy@google.com> on 2011-11-04

* platform/audio/Biquad.cpp:
(WebCore::Biquad::getFrequencyResponse):
Computes the magnitude and phase (radians) response for the given
biquad at the specified set of (normalized) frequencies.
* platform/audio/Biquad.h:
Declare getFrequencyResponse.
* webaudio/BiquadDSPKernel.cpp:
(WebCore::BiquadDSPKernel::updateCoefficientsIfNecessary):
Factor out the code that updates filter coefficients.  Allow the
caller to specify whether the smoothed values are used or not and
whether we do the update even if the coefficients are not dirty.
(WebCore::BiquadDSPKernel::process):
Use updateCoefficientsIfNecessary to update.
(WebCore::BiquadDSPKernel::getFrequencyResponse):
Implmentation of getFrequencyResponse.
* webaudio/BiquadDSPKernel.h:
Declare getFrequencyResponse.
* webaudio/BiquadFilterNode.cpp:
(WebCore::BiquadFilterNode::getFrequencyResponse):
Implementation of getFrequencyResponse
* webaudio/BiquadFilterNode.h:
Declare getFrequencyResponse.
* webaudio/BiquadFilterNode.idl:
Define interface to getFrequencyResponse.
* webaudio/BiquadProcessor.cpp:
(WebCore::BiquadProcessor::checkForDirtyCoefficients):
Factor out code for checking for dirty coefficients.
(WebCore::BiquadProcessor::process):
Use checkForDirtyCoefficients.
(WebCore::BiquadProcessor::getFrequencyResponse):
Implementation of getFrequencyResponse
* webaudio/BiquadProcessor.h:
Declare getFrequencyResponse.

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@99337 268f45cc-cd09-0410-ab3c-d52691b4dbfc