[css3-text] Implement text-decoration property shorthand

Source/core/css/CSSParser-in.cpp

Index: Source/core/css/CSSParser-in.cpp
diff --git a/Source/core/css/CSSParser-in.cpp b/Source/core/css/CSSParser-in.cpp
index 71f660d76dc269ea797e5f132392deedbee6d87d..86ab94acb50bd3e5a2a1b27c3a43f5ae2fcf2168 100644
--- a/Source/core/css/CSSParser-in.cpp
+++ b/Source/core/css/CSSParser-in.cpp
@@ -2118,6 +2118,11 @@ bool CSSParser::parseValue(CSSPropertyID propId, bool important)
     }
 
     case CSSPropertyTextDecoration:
+        // Fall through to CSS2.1 implementation if runtime feature is disabled.
+        if (RuntimeEnabledFeatures::css3TextDecorationsEnabled()) {
+            // [ <text-decoration-line> || <text-decoration-style> || <text-decoration-color> ] | inherit
+            return parseShorthand(CSSPropertyTextDecoration, textDecorationShorthand(), important);
+        }
     case CSSPropertyWebkitTextDecorationsInEffect:
     case CSSPropertyTextDecorationLine:
         // none | [ underline || overline || line-through || blink ] | inherit
@@ -8885,7 +8890,8 @@ bool CSSParser::parseTextDecoration(CSSPropertyID propId, bool important)
             value = m_valueList->next();
     }
 
-    if (list->length() && isValid) {
+    // Values are either valid or in shorthand scope.
+    if (list->length() && (isValid || inShorthand())) {
         addTextDecorationProperty(propId, list.release(), important);
         return true;
     }