Remove some includes from image-related headers, and Document.h

Remove some includes from image-related headers, and Document.h
https://bugs.webkit.org/show_bug.cgi?id=131797

Reviewed by Martin Robinson.

Remove some #includes from Document.h, DragImage.h, GradientImage.h,
Image.h, and ImageBuffer.h and deal with the fallout.

* dom/ContainerNode.h:
* dom/Document.cpp:
(WebCore::Document::setInputCursor):
* dom/Document.h:
(WebCore::Document::inputCursor):
* dom/MutationObserverRegistration.cpp:
* html/canvas/WebGLRenderingContext.cpp:
* page/FrameSnapshotting.cpp:
* page/Page.cpp:
* platform/DragImage.h:
* platform/graphics/BitmapImage.cpp:
* platform/graphics/GradientImage.cpp:
(WebCore::GradientImage::GradientImage):
(WebCore::GradientImage::~GradientImage):
* platform/graphics/GradientImage.h:
* platform/graphics/Image.h:
* platform/graphics/ImageBuffer.cpp:
* platform/graphics/ImageBuffer.h:
(WebCore::ImageBuffer::create):
(WebCore::ImageBuffer::internalSize):
(WebCore::ImageBuffer::logicalSize):
(WebCore::ImageBuffer::baseTransform):
(WebCore::ImageBuffer::spaceSize):
(WebCore::ImageBuffer::setSpaceSize):
* rendering/RenderThemeMac.mm:
* rendering/shapes/Shape.cpp:
* rendering/svg/RenderSVGContainer.cpp:
* svg/SVGURIReference.h:

git-svn-id: https://svn.webkit.org/repository/webkit/trunk@167497 268f45cc-cd09-0410-ab3c-d52691b4dbfc