Fix setting css-wide keywords on registered custom properties

third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp

Index: third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
diff --git a/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp b/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
index 56c252edc71bf0f05bcb6bc5fd9340c87efd9e6d..a6549ffef62e597e8f60d5a229faba1c351ebaab 100644
--- a/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
+++ b/third_party/WebKit/Source/core/css/parser/CSSParserImpl.cpp
@@ -81,7 +81,9 @@ MutableStylePropertySet::SetResult CSSParserImpl::parseVariableValue(
   bool didParse = false;
   bool didChange = false;
   if (!parser.m_parsedProperties.isEmpty()) {
-    if (registry) {
+    const CSSCustomPropertyDeclaration* parsedDeclaration =
+        toCSSCustomPropertyDeclaration(parser.m_parsedProperties[0].value());
+    if (parsedDeclaration->value() && registry) {
       const PropertyRegistry::Registration* registration =
           registry->registration(propertyName);
       // TODO(timloh): This is a bit wasteful, we parse the registered property