Add support for gradients in the CSS content property.

        Reviewed by olliej

        Added fast/gradients/generated-gradients.html

        * GNUmakefile.am:
        * WebCore.pro:
        * WebCore.vcproj/WebCore.vcproj:
        * WebCore.xcodeproj/project.pbxproj:
        * WebCoreSources.bkl:
        * css/CSSParser.cpp:
        (WebCore::CSSParser::parseContent):
        * css/CSSStyleSelector.cpp:
        (WebCore::CSSStyleSelector::applyProperty):
        (WebCore::CSSStyleSelector::styleImage):
        (WebCore::CSSStyleSelector::mapBackgroundImage):
        * css/CSSStyleSelector.h:
        * html/HTMLImageElement.cpp:
        (WebCore::HTMLImageElement::attach):
        * rendering/RenderContainer.cpp:
        (WebCore::RenderContainer::updateBeforeAfterContentForContainer):
        * rendering/RenderImage.cpp:
        (WebCore::RenderImage::RenderImage):
        (WebCore::RenderImage::setCachedImage):
        (WebCore::RenderImage::paintReplaced):
        (WebCore::RenderImage::calcReplacedWidth):
        (WebCore::RenderImage::calcReplacedHeight):
        (WebCore::RenderImage::calcAspectRatioWidth):
        (WebCore::RenderImage::calcAspectRatioHeight):
        * rendering/RenderImage.h:
        (WebCore::RenderImage::hasImage):
        (WebCore::RenderImage::image):
        (WebCore::RenderImage::errorOccurred):
        (WebCore::RenderImage::usesImageContainerSize):
        (WebCore::RenderImage::setImageContainerSize):
        (WebCore::RenderImage::imageHasRelativeWidth):
        (WebCore::RenderImage::imageHasRelativeHeight):
        (WebCore::RenderImage::imageSize):
        * rendering/RenderImageGeneratedContent.cpp: Added.
        (WebCore::RenderImageGeneratedContent::RenderImageGeneratedContent):
        (WebCore::RenderImageGeneratedContent::~RenderImageGeneratedContent):
        (WebCore::RenderImageGeneratedContent::setStyleImage):
        * rendering/RenderImageGeneratedContent.h: Added.
        (WebCore::RenderImageGeneratedContent::hasImage):
        (WebCore::RenderImageGeneratedContent::image):
        (WebCore::RenderImageGeneratedContent::errorOccurred):
        (WebCore::RenderImageGeneratedContent::usesImageContainerSize):
        (WebCore::RenderImageGeneratedContent::setImageContainerSize):
        (WebCore::RenderImageGeneratedContent::imageHasRelativeWidth):
        (WebCore::RenderImageGeneratedContent::imageHasRelativeHeight):
        (WebCore::RenderImageGeneratedContent::imageSize):
        * rendering/RenderObject.cpp:
        (WebCore::RenderObject::createObject):
        * rendering/RenderStyle.cpp:
        (WebCore::StyleCachedImage::imageHasRelativeWidth):
        (WebCore::StyleCachedImage::imageHasRelativeHeight):
        (WebCore::StyleCachedImage::usesImageContainerSize):
        (WebCore::RenderStyle::contentDataEquivalent):
        (WebCore::RenderStyle::setContent):
        (WebCore::ContentData::clear):
        * rendering/RenderStyle.h:
        (WebCore::StyleGeneratedImage::imageHasRelativeWidth):
        (WebCore::StyleGeneratedImage::imageHasRelativeHeight):
        (WebCore::StyleGeneratedImage::usesImageContainerSize):
        (WebCore::BackgroundLayer::setBackgroundImage):
        (WebCore::ContentData::):
        (WebCore::RenderStyle::setListStyleImage):



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@31873 268f45cc-cd09-0410-ab3c-d52691b4dbfc