[Variables] Enable get/setProperty and similar APIs from the CSSOM

third_party/WebKit/Source/build/scripts/templates/CSSPropertyMetadata.cpp.tmpl

Index: third_party/WebKit/Source/build/scripts/templates/CSSPropertyMetadata.cpp.tmpl
diff --git a/third_party/WebKit/Source/build/scripts/templates/CSSPropertyMetadata.cpp.tmpl b/third_party/WebKit/Source/build/scripts/templates/CSSPropertyMetadata.cpp.tmpl
index 9c822ae008617f43447a23f28d4ef0ee8cca0fb1..cdccc1d39e48e813d35ac2287ce418ac3426ebbd 100644
--- a/third_party/WebKit/Source/build/scripts/templates/CSSPropertyMetadata.cpp.tmpl
+++ b/third_party/WebKit/Source/build/scripts/templates/CSSPropertyMetadata.cpp.tmpl
@@ -26,21 +26,28 @@ bool CSSPropertyMetadata::{{function_name}}(CSSPropertyID property)
 }
 {% endfor %}
 
+// There is one more valid property ID than the total count of CSS properties
+// because of custom properties.
+static const int numValidPropertyIDs = numCSSProperties + 1;
+
 bool CSSPropertyMetadata::isEnabledProperty(CSSPropertyID unresolvedProperty)
 {
     CSSPropertyID property = resolveCSSPropertyID(unresolvedProperty);
-    static BitArray<numCSSProperties>* enabledProperties = 0;
+    static BitArray<numValidPropertyIDs>* enabledProperties = 0;
     if (!enabledProperties) {
-        enabledProperties = new BitArray<numCSSProperties>(true); // All bits sets to 1.
+        enabledProperties = new BitArray<numValidPropertyIDs>(true); // All bits sets to 1.
+        static_assert(CSSPropertyVariable == {{first_enum_value - 1}}, "CSSPropertyVariable should directly precede first_enum_value.");
+        if (!RuntimeEnabledFeatures::cssVariablesEnabled())
+            enabledProperties->clear(0);
         {% for property_id, property in properties.items() if property.runtime_flag %}
         if (!RuntimeEnabledFeatures::{{property.runtime_flag|lower_first}}Enabled())
-            enabledProperties->clear({{property_id}} - {{first_enum_value}});
+            enabledProperties->clear({{property_id}} - {{first_enum_value - 1}});
         {% endfor %}
         {% for property_id, property in properties.items() if property.is_internal %}
-        enabledProperties->clear({{property_id}} - {{first_enum_value}});
+        enabledProperties->clear({{property_id}} - {{first_enum_value - 1}});
         {% endfor %}
     }
-    return enabledProperties->get(property - {{first_enum_value}});
+    return enabledProperties->get(property - {{first_enum_value - 1}});
 }
 
 void CSSPropertyMetadata::filterEnabledCSSPropertiesIntoVector(const CSSPropertyID* properties, size_t propertyCount, Vector<CSSPropertyID>& outVector)