Add support for [TreatNullAs] extended attribute for reflected attributes

Source/core/html/HTMLTableElement.idl

Index: Source/core/html/HTMLTableElement.idl
diff --git a/Source/core/html/HTMLTableElement.idl b/Source/core/html/HTMLTableElement.idl
index 1881de3ea17cb32c5f3bf339b9ced7a056bd17b3..cd247d62798a76e9a8fe3aa00ca85b18549b3bbe 100644
--- a/Source/core/html/HTMLTableElement.idl
+++ b/Source/core/html/HTMLTableElement.idl
@@ -25,17 +25,17 @@ interface HTMLTableElement : HTMLElement {
 
     readonly attribute HTMLCollection rows;
     readonly attribute HTMLCollection tBodies;
-    [Reflect] attribute DOMString align;
-    [Reflect] attribute DOMString bgColor;
-    [Reflect] attribute DOMString border;
-    [Reflect] attribute DOMString cellPadding;
-    [Reflect] attribute DOMString cellSpacing;
+    [Reflect, TreatNullAs=NullString] attribute DOMString align;
+    [Reflect, TreatNullAs=NullString] attribute DOMString bgColor;
+    [Reflect, TreatNullAs=NullString] attribute DOMString border;
+    [Reflect, TreatNullAs=NullString] attribute DOMString cellPadding;
+    [Reflect, TreatNullAs=NullString] attribute DOMString cellSpacing;
 
-    [Reflect] attribute DOMString frame;
+    [Reflect, TreatNullAs=NullString] attribute DOMString frame;
 
-    [Reflect] attribute DOMString rules;
-    [Reflect] attribute DOMString summary;
-    [Reflect] attribute DOMString width;
+    [Reflect, TreatNullAs=NullString] attribute DOMString rules;
+    [Reflect, TreatNullAs=NullString] attribute DOMString summary;
+    [Reflect, TreatNullAs=NullString] attribute DOMString width;
 
     HTMLElement createTHead();
     void deleteTHead();