Reviewed by David Hyatt.

        Implement -webkit-linear-gradient and -webkit-radial-gradient
        https://bugs.webkit.org/show_bug.cgi?id=28152

        Add support for -webkit-radial-gradients.

        Tests: fast/gradients/css3-radial-gradients.html
               fast/gradients/css3-radial-gradients2.html

        * css/CSSGradientValue.cpp:
        (WebCore::blend): Used to blend colors, which is necessary when truncating
        the start of radial gradients.
        (WebCore::GradientStop): Small struct to aid gradient stop processing.
        (WebCore::CSSGradientValue::addStops): Rename 'positions' to 'stops', and store
        the color so that we can blend it when truncating radial gradients. Changed
        to handle both linear and radial gradients.
        (WebCore::CSSRadialGradientValue::cssText): Update to follow the spec.
        (WebCore::CSSRadialGradientValue::resolveRadius): Stylistic change.
        (WebCore::distanceToClosestCorner): New utility method.
        (WebCore::distanceToFarthestCorner): Ditto.
        (WebCore::CSSRadialGradientValue::createGradient): New logic to deal with shape and
        fill rules.

        * css/CSSGradientValue.h:
        (WebCore::CSSGradientValue::isLinearGradient): Color-stop processing needs to know what
        kind of gradient it's dealing with, so add new isFooGradient methods.
        (WebCore::CSSGradientValue::isRadialGradient): Ditto.
        (WebCore::CSSLinearGradientValue::isLinearGradient):
        (WebCore::CSSRadialGradientValue::setShape): New setters for shape, size etc.
        (WebCore::CSSRadialGradientValue::setSizingBehavior):
        (WebCore::CSSRadialGradientValue::setEndHorizontalSize):
        (WebCore::CSSRadialGradientValue::setEndVerticalSize):
        (WebCore::CSSRadialGradientValue::isRadialGradient):

        * css/CSSParser.h:
        * css/CSSParser.h: Pass a CSSParserValueList* into parseFillPositionXY() and parseFillPosition()
        so we can use parseFillPosition() when parsing a gradient function.
        * css/CSSParser.cpp:
        (WebCore::CSSParser::parseFillPositionXY): Pass in a CSSParserValueList*
        (WebCore::CSSParser::parseFillPosition): Ditto
        (WebCore::CSSParser::parseFillProperty): Pass m_valueList to parseFillPosition.
        (WebCore::CSSParser::parseTransformOriginShorthand): Ditto
        (WebCore::CSSParser::parseRadialGradient): Flesh out radial gradient parsing.
        (WebCore::CSSParser::parseTransformOrigin): Pass m_valueList to parseFillPosition.
        (WebCore::CSSParser::parsePerspectiveOrigin): Ditto

        * css/CSSValueKeywords.in: New keywords for radial gradient shape and fill behaviors.

        * platform/graphics/Gradient.cpp:
        (WebCore::Gradient::Gradient): Pass aspect ratio for elliptical gradients.
        * platform/graphics/Gradient.h: Add aspect ratio for elliptical gradients.
        (WebCore::Gradient::create):
        (WebCore::Gradient::startRadius): Expose radii.
        (WebCore::Gradient::endRadius):
        (WebCore::Gradient::setStartRadius): Setters are required for when we need to scale color stops.
        (WebCore::Gradient::setEndRadius):
        (WebCore::Gradient::aspectRatio):
        * platform/graphics/cg/GradientCG.cpp:
        (WebCore::Gradient::paint): For elliptical gradients, scale the CTM.
        * platform/graphics/wince/GraphicsContextWinCE.cpp:
        (WebCore::GraphicsContext::fillRect): Use start/endRadius() rather than r0() and r1().

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@74915 268f45cc-cd09-0410-ab3c-d52691b4dbfc