Add support for the column-fill property.

Source/core/css/CSSComputedStyleDeclaration.cpp

Index: Source/core/css/CSSComputedStyleDeclaration.cpp
diff --git a/Source/core/css/CSSComputedStyleDeclaration.cpp b/Source/core/css/CSSComputedStyleDeclaration.cpp
index b3cf2ba0f2a05e486730523a4be5746ce0315951..f4a18eb406d47185acf57b1e8f221cccd1aac5bb 100644
--- a/Source/core/css/CSSComputedStyleDeclaration.cpp
+++ b/Source/core/css/CSSComputedStyleDeclaration.cpp
@@ -1909,6 +1909,10 @@ PassRefPtr<CSSValue> CSSComputedStyleDeclaration::getPropertyCSSValue(CSSPropert
             if (style->hasAutoColumnCount())
                 return cssValuePool().createIdentifierValue(CSSValueAuto);
             return cssValuePool().createValue(style->columnCount(), CSSPrimitiveValue::CSS_NUMBER);
+        case CSSPropertyColumnFill:
+            if (RuntimeEnabledFeatures::regionBasedColumnsEnabled())
+                return cssValuePool().createValue(style->columnFill());
+            return 0;
         case CSSPropertyWebkitColumnGap:
             if (style->hasNormalColumnGap())
                 return cssValuePool().createIdentifierValue(CSSValueNormal);