*** NOT FOR LANDING *** Unprefix multicol behind a flag

Source/core/css/CSSProperties.in

 // This file specifies all the CSS properties we support and the necessary
 // information for our code generation. The various supported arguments
 // are described below with example usage
 
 
 // - alias_for=other-property
 // Properties specifying alias_for should be virtually identical to the
 // properties they alias. Minor parsing differences are allowed as long as
 // the CSSValues created are of the same format of the aliased property.
 
@@ skipping 141 matching lines @@
 box-sizing
 buffered-rendering svg
 caption-side inherited
 clear
 clip animatable, converter=convertClip, custom_all
 clip-path svg, name_for_methods=ClipperResource, converter=convertFragmentIdentifier
 clip-rule inherited, svg, type_name=WindRule
 color-interpolation inherited, svg
 color-interpolation-filters inherited, svg, type_name=EColorInterpolation
 color-rendering inherited, svg
-column-fill runtime_flag=RegionBasedColumns, type_name=ColumnFill
+column-count animatable, type_name=unsigned short, custom_all
+column-fill runtime_flag=UnprefixMulticol, type_name=ColumnFill
+column-gap animatable, converter=convertComputedLength<float>, custom_all
+column-rule-color animatable, custom_all
+column-rule-style type_name=EBorderStyle, initial=initialBorderStyle
+column-rule-width animatable, converter=convertLineWidth<unsigned short>
+column-span type_name=ColumnSpan
+column-width animatable, converter=convertComputedLength<float>, custom_all
 content custom_all
 counter-increment custom_all
 counter-reset custom_all
 cursor inherited, custom_all
 cx animatable, svg, converter=convertLength
 cy animatable, svg, converter=convertLength
 display
 dominant-baseline svg
 empty-cells inherited, type_name=EEmptyCell
 fill animatable, inherited, svg, setter=setFillPaint, custom_all
@@ skipping 145 matching lines @@
 -webkit-box-flex-group type_name=unsigned int
 -webkit-box-lines
 -webkit-box-ordinal-group type_name=unsigned int
 -webkit-box-orient
 -webkit-box-pack
 -webkit-box-reflect converter=convertBoxReflect
 -webkit-clip-path animatable, custom_value
 -webkit-column-break-after type_name=EPageBreak, initial=initialPageBreak
 -webkit-column-break-before type_name=EPageBreak, initial=initialPageBreak
 -webkit-column-break-inside type_name=EPageBreak, initial=initialPageBreak
--webkit-column-count animatable, type_name=unsigned short, custom_all
--webkit-column-gap animatable, converter=convertComputedLength<float>, custom_all
--webkit-column-rule-color animatable, custom_all
--webkit-column-rule-style type_name=EBorderStyle, initial=initialBorderStyle
--webkit-column-rule-width animatable, converter=convertLineWidth<unsigned short>
--webkit-column-span type_name=ColumnSpan
--webkit-column-width animatable, converter=convertComputedLength<float>, custom_all
 -webkit-filter animatable, custom_value
 -webkit-highlight inherited, converter=convertString<CSSValueNone>
 -webkit-hyphenate-character inherited, name_for_methods=HyphenationString, converter=convertString<CSSValueAuto>
 -webkit-line-box-contain inherited, converter=convertLineBoxContain
 -webkit-line-break inherited, type_name=LineBreak
 -webkit-line-clamp type_name=LineClampValue
 -webkit-margin-after-collapse type_name=EMarginCollapse
 -webkit-margin-before-collapse type_name=EMarginCollapse
 -webkit-margin-bottom-collapse type_name=EMarginCollapse, name_for_methods=MarginAfterCollapse
 -webkit-margin-top-collapse type_name=EMarginCollapse, name_for_methods=MarginBeforeCollapse
@@ skipping 96 matching lines @@
 border-bottom longhands=border-bottom-width;border-bottom-style;border-bottom-color
 border-color longhands=border-top-color;border-right-color;border-bottom-color;border-left-color
 border-image longhands=border-image-source;border-image-slice;border-image-width;border-image-outset;border-image-repeat
 border-left longhands=border-left-width;border-left-style;border-left-color
 border-radius longhands=border-top-left-radius;border-top-right-radius;border-bottom-right-radius;border-bottom-left-radius
 border-right longhands=border-right-width;border-right-style;border-right-color
 border-spacing longhands=-webkit-border-horizontal-spacing;-webkit-border-vertical-spacing
 border-style longhands=border-top-style;border-right-style;border-bottom-style;border-left-style
 border-top longhands=border-top-width;border-top-style;border-top-color
 border-width longhands=border-top-width;border-right-width;border-bottom-width;border-left-width
+column-rule longhands=column-rule-width;column-rule-style;column-rule-color
+columns longhands=column-width;column-count
 flex longhands=flex-grow;flex-shrink;flex-basis
 flex-flow longhands=flex-direction;flex-wrap
 font longhands=font-family;font-size;font-style;font-variant;font-weight;font-stretch;line-height
 grid runtime_flag=CSSGridLayout, longhands=grid-template-columns;grid-template-rows;grid-template-areas;grid-auto-flow;grid-auto-columns;grid-auto-rows
 grid-area runtime_flag=CSSGridLayout, longhands=grid-row-start;grid-column-start;grid-row-end;grid-column-end
 grid-column runtime_flag=CSSGridLayout, longhands=grid-column-start;grid-column-end
 grid-row runtime_flag=CSSGridLayout, longhands=grid-row-start;grid-row-end
 grid-template runtime_flag=CSSGridLayout, longhands=grid-template-columns;grid-template-rows;grid-template-areas
 list-style longhands=list-style-type;list-style-position;list-style-image
 margin longhands=margin-top;margin-right;margin-bottom;margin-left
 marker longhands=marker-start;marker-mid;marker-end
 motion runtime_flag=CSSMotionPath, longhands=motion-path;motion-offset;motion-rotation
 outline longhands=outline-color;outline-style;outline-width
 overflow longhands=overflow-x;overflow-y
 padding longhands=padding-top;padding-right;padding-bottom;padding-left
 transition longhands=transition-property;transition-duration;transition-timing-function;transition-delay
 -webkit-border-after longhands=-webkit-border-after-width;-webkit-border-after-style;-webkit-border-after-color
 -webkit-border-before longhands=-webkit-border-before-width;-webkit-border-before-style;-webkit-border-before-color
 -webkit-border-end longhands=-webkit-border-end-width;-webkit-border-end-style;-webkit-border-end-color
 -webkit-border-start longhands=-webkit-border-start-width;-webkit-border-start-style;-webkit-border-start-color
--webkit-column-rule longhands=-webkit-column-rule-width;-webkit-column-rule-style;-webkit-column-rule-color
--webkit-columns longhands=-webkit-column-width;-webkit-column-count
 -webkit-margin-collapse longhands=-webkit-margin-before-collapse;-webkit-margin-after-collapse
 -webkit-mask longhands=-webkit-mask-image;-webkit-mask-position-x;-webkit-mask-position-y;-webkit-mask-size;-webkit-mask-repeat-x;-webkit-mask-repeat-y;-webkit-mask-origin;-webkit-mask-clip
 -webkit-mask-box-image longhands=-webkit-mask-box-image-source;-webkit-mask-box-image-slice;-webkit-mask-box-image-width;-webkit-mask-box-image-outset;-webkit-mask-box-image-repeat
 -webkit-mask-position longhands=-webkit-mask-position-x;-webkit-mask-position-y
 -webkit-mask-repeat longhands=-webkit-mask-repeat-x;-webkit-mask-repeat-y
 -webkit-text-emphasis longhands=-webkit-text-emphasis-style;-webkit-text-emphasis-color
 -webkit-text-stroke longhands=-webkit-text-stroke-width;-webkit-text-stroke-color
 
 // Aliases; these map to the same CSSPropertyID
 
@@ skipping 22 matching lines @@
 // "-webkit-background-size: 10px" behaves as "background-size: 10px 10px"
 -webkit-background-size alias_for=background-size
 -webkit-border-bottom-left-radius alias_for=border-bottom-left-radius
 -webkit-border-bottom-right-radius alias_for=border-bottom-right-radius
 // "-webkit-border-radius: 1px 2px" behaves as "border-radius: 1px / 2px"
 -webkit-border-radius alias_for=border-radius
 -webkit-border-top-left-radius alias_for=border-top-left-radius
 -webkit-border-top-right-radius alias_for=border-top-right-radius
 -webkit-box-shadow alias_for=box-shadow
 -webkit-box-sizing alias_for=box-sizing
+-webkit-column-count alias_for=column-count
+-webkit-column-gap alias_for=column-gap
+-webkit-column-rule alias_for=column-rule
+-webkit-column-rule-color alias_for=column-rule-color
+-webkit-column-rule-style alias_for=column-rule-style
+-webkit-column-rule-width alias_for=column-rule-width
+-webkit-column-span alias_for=column-span
+-webkit-column-width alias_for=column-width
+-webkit-columns alias_for=columns
 -webkit-flex alias_for=flex
 -webkit-flex-basis alias_for=flex-basis
 -webkit-flex-direction alias_for=flex-direction
 -webkit-flex-flow alias_for=flex-flow
 -webkit-flex-grow alias_for=flex-grow
 -webkit-flex-shrink alias_for=flex-shrink
 -webkit-flex-wrap alias_for=flex-wrap
 -webkit-justify-content alias_for=justify-content
 -webkit-opacity alias_for=opacity
 -webkit-order alias_for=order
 -webkit-perspective alias_for=perspective
 -webkit-perspective-origin alias_for=perspective-origin
 -webkit-shape-image-threshold alias_for=shape-image-threshold
 -webkit-shape-margin alias_for=shape-margin
 -webkit-shape-outside alias_for=shape-outside
 -webkit-transform alias_for=transform
 -webkit-transform-origin alias_for=transform-origin
 -webkit-transform-style alias_for=transform-style
 -webkit-transition alias_for=transition
 -webkit-transition-delay alias_for=transition-delay
 -webkit-transition-duration alias_for=transition-duration
 -webkit-transition-property alias_for=transition-property
 -webkit-transition-timing-function alias_for=transition-timing-function