https://bugs.webkit.org/show_bug.cgi?id=96801

Reviewed by Dean Jackson.

I've refactored the FECustomFilter to allow FECustomFilterSkia.cpp to use the rendering part
from outside.

Also removed the Texture class as it is not available on some platforms.

The changes for Skia will land in a different patch:
https://bugs.webkit.org/show_bug.cgi?id=96579

No new tests, the existing custom filters tests should already cover this.

* platform/graphics/filters/CustomFilterGlobalContext.cpp:
(WebCore::CustomFilterGlobalContext::prepareContextIfNeeded):
* platform/graphics/filters/FECustomFilter.cpp:
(WebCore::FECustomFilter::FECustomFilter):
(WebCore::FECustomFilter::deleteRenderBuffers):
(WebCore::FECustomFilter::drawFilterMesh):
(WebCore):
(WebCore::FECustomFilter::prepareForDrawing):
(WebCore::FECustomFilter::programNeedsInputTexture):
(WebCore::FECustomFilter::applyShader):
(WebCore::FECustomFilter::initializeContext):
(WebCore::FECustomFilter::ensureInputTexture):
(WebCore::FECustomFilter::uploadInputTexture):
(WebCore::FECustomFilter::ensureFrameBuffer):
(WebCore::FECustomFilter::resizeContextIfNeeded):
(WebCore::FECustomFilter::resizeContext):
(WebCore::FECustomFilter::bindProgramAndBuffers):
* platform/graphics/filters/FECustomFilter.h:
(FECustomFilter):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@128641 268f45cc-cd09-0410-ab3c-d52691b4dbfc