Reviewed by Alexey Proskuryakov.

        - fix a leak when using hex color values in CSS variables

        - fix CSSOM access to hex color values in variables declarations

        Test: fast/css/variables/color-hex-test.html

        Added a new unit/type, CSS_PARSER_HEXCOLOR, which serves as the unit for
        CSSParserValues coming from colors in hex notation. CSSParserValues can
        no longer have CSS_RGBCOLOR as their unit. CSS_PARSER_HEXCOLOR is also
        used as the type for CSSValues in CSS variables declarations where the
        parser value was a hex color. However the type of all other color
        CSSValues remains CSS_RGBCOLOR.

        * css/CSSGrammar.y: Changed to use the new CSS_PARSER_HEXCOLOR value
        for color values in hex notation.
        * css/CSSParser.cpp:
        (WebCore::CSSParser::parseColorFromValue): Updated for the new unit.
        * css/CSSParserValues.cpp:
        (WebCore::CSSParserValue::createCSSValue): Ditto.
        * css/CSSPrimitiveValue.cpp:
        (WebCore::CSSPrimitiveValue::cleanup): Fixed the leak by deref()ing the
        string containing the color.
        (WebCore::CSSPrimitiveValue::cssText): Added support for
        CSS_PARSER_HEXCOLOR for when serializing variable values.
        (WebCore::CSSPrimitiveValue::parserValue): Updated for the new unit.
        * css/CSSPrimitiveValue.h:
        (WebCore::CSSPrimitiveValue::): Added a new unti, CSS_PARSER_HEXCOLOR.

LayoutTests:

        Reviewed by Alexey Proskuryakov.

        - updated test to cover serializing variable values which are colors in
          hex notation

        * fast/css/variables/color-hex-test.html:



git-svn-id: http://svn.webkit.org/repository/webkit/trunk@35320 268f45cc-cd09-0410-ab3c-d52691b4dbfc