[css-align] Implement place-content alignment shorthand

third_party/WebKit/Source/core/css/StylePropertySerializer.cpp

Index: third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
diff --git a/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp b/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
index 9314b06ae97423589b461c50200d0c9f4609b704..edca4c4aefafcb7f534810fff6309479251d0b97 100644
--- a/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
+++ b/third_party/WebKit/Source/core/css/StylePropertySerializer.cpp
@@ -454,6 +454,8 @@ String StylePropertySerializer::getPropertyValue(
       return getShorthandValue(gridAreaShorthand(), " / ");
     case CSSPropertyGridGap:
       return getShorthandValue(gridGapShorthand());
+    case CSSPropertyPlaceContent:
+      return placeContentPropertyValue();
     case CSSPropertyFont:
       return fontValue();
     case CSSPropertyFontVariant:
@@ -848,6 +850,13 @@ String StylePropertySerializer::getCommonValue(
   return res;
 }
 
+String StylePropertySerializer::placeContentPropertyValue() const {
+  String value = getCommonValue(placeContentShorthand());
+  if (value.isNull() || value.isEmpty())
+    return getShorthandValue(placeContentShorthand());
+  return value;
+}
+
 String StylePropertySerializer::borderPropertyValue() const {
   const StylePropertyShorthand properties[3] = {
       borderWidthShorthand(), borderStyleShorthand(), borderColorShorthand()};