I have added Project Ribbon support for css aliases by way of CSSUnresolvedProperty and its direct subclasses. We need this because aliases have leaked out into the engine past the parser in some places.

Once we finish replacing as many CSSPropertyIDs with CSS(Unresolved)Property references, we can take stock of and hopefully remove these leaks. Then CSSUnresolvedProperty and its subclasses can be removed.

Alias properties are
EpubCaptionSide
EpubTextCombine
EpubTextEmphasis
EpubTextEmphasisColor
EpubTextEmphasisStyle
EpubTextOrientation
EpubTextTransform
EpubWordBreak
EpubWritingMode
WebkitAlignContent
WebkitAlignItems
WebkitAlignSelf
WebkitAnimation
WebkitAnimationDelay
WebkitAnimationDirection
WebkitAnimationDuration
WebkitAnimationFillMode
WebkitAnimationIterationCount
WebkitAnimationName
WebkitAnimationPlayState
WebkitAnimationTimingFunction
WebkitBackfaceVisibility
WebkitBackgroundClip
WebkitBackgroundOrigin
WebkitBackgroundSize
WebkitBorderBottomLeftRadius
WebkitBorderBottomRightRadius
WebkitBorderRadius
WebkitBorderTopLeftRadius
WebkitBorderTopRightRadius
WebkitBoxShadow
WebkitBoxSizing
WebkitClipPath
WebkitColumnCount
WebkitColumnGap
WebkitColumnRule
WebkitColumnRuleColor
WebkitColumnRuleStyle
WebkitColumnRuleWidth
WebkitColumnSpan
WebkitColumnWidth
WebkitColumns
WebkitFilter
WebkitFlex
WebkitFlexBasis
WebkitFlexDirection
WebkitFlexFlow
WebkitFlexGrow
WebkitFlexShrink
WebkitFlexWrap
WebkitFontFeatureSettings
WebkitJustifyContent
WebkitOpacity
WebkitOrder
WebkitPerspective
WebkitPerspectiveOrigin
WebkitShapeImageThreshold
WebkitShapeMargin
WebkitShapeOutside
WebkitTextSizeAdjust
WebkitTransform
WebkitTransformOrigin
WebkitTransformStyle
WebkitTransition
WebkitTransitionDelay
WebkitTransitionDuration
WebkitTransitionProperty
WebkitTransitionTimingFunction
WebkitUserSelect