Improve test coverage of TreatNullAs=NullString and TreatUndefinedAs=NullString

Source/bindings/tests/idls/TestObject.idl

Index: Source/bindings/tests/idls/TestObject.idl
diff --git a/Source/bindings/tests/idls/TestObject.idl b/Source/bindings/tests/idls/TestObject.idl
index 628570260c91deada3511b552cd40248948b3e27..83fabe536a6aea5925f01f05cbe2027175db22e9 100644
--- a/Source/bindings/tests/idls/TestObject.idl
+++ b/Source/bindings/tests/idls/TestObject.idl
@@ -54,6 +54,8 @@ callback TestCallbackFunction = void (TestEnumType formal1, TestObject formal2);
     attribute long long                longLongAttr;
     attribute unsigned long long       unsignedLongLongAttr;
     attribute DOMString                stringAttr;
+    [TreatNullAs=NullString] attribute DOMString treatNullAsNullStringStringAttr;
+    [TreatNullAs=NullString, TreatUndefinedAs=NullString] attribute DOMString treatNullAsNullStringTreatUndefinedAsNullStringStringAttr;
     attribute EventHandler             eventHandlerAttr;
     [MeasureAs=TestFeature] attribute TestObject testObjAttr;
     [ExposeJSAccessors] attribute DOMString attrWithJSGetterAndSetter;
@@ -63,15 +65,23 @@ callback TestCallbackFunction = void (TestEnumType formal1, TestObject formal2);
     attribute boolean                  create;
 
     // Reflected DOM attributes
-    [Reflect, TreatNullAs=NullString] attribute DOMString reflectedStringAttr;
+    [Reflect] attribute DOMString reflectedStringAttr;
+    [Reflect, TreatNullAs=NullString] attribute DOMString reflectedTreatNullAsNullStringStringAttr;
+    [Reflect, TreatNullAs=NullString, TreatUndefinedAs=NullString] attribute DOMString reflectedTreatNullAsNullStringTreatUndefinedAsNullStringStringAttr;
     [Reflect] attribute long reflectedIntegralAttr;
     [Reflect] attribute unsigned long reflectedUnsignedIntegralAttr;
     [Reflect] attribute boolean reflectedBooleanAttr;
-    [Reflect, TreatNullAs=NullString, URL] attribute DOMString reflectedURLAttr;
-    [Reflect=customContentStringAttr, TreatNullAs=NullString] attribute DOMString reflectedStringAttr;
+    [Reflect, URL] attribute DOMString reflectedURLAttr;
+    [Reflect, TreatNullAs=NullString, URL] attribute DOMString reflectedTreatNullAsNullStringURLAttr;
+    [Reflect, TreatNullAs=NullString, TreatUndefinedAs=NullString, URL] attribute DOMString reflectedTreatNullAsNullStringTreatUndefinedAsNullStringURLAttr;
+    [Reflect=customContentStringAttr] attribute DOMString reflectedCustomStringAttr;
+    [Reflect=customContentStringAttr, TreatNullAs=NullString] attribute DOMString reflectedTreatNullAsNullStringCustomStringAttr;
+    [Reflect=customContentStringAttr, TreatNullAs=NullString, TreatUndefinedAs=NullString] attribute DOMString reflectedTreatNullAsNullStringTreatUndefinedAsNullStringCustomStringAttr;
     [Reflect=customContentIntegralAttr] attribute long reflectedCustomIntegralAttr;
     [Reflect=customContentBooleanAttr] attribute boolean reflectedCustomBooleanAttr;
-    [Reflect=customContentURLAttr, TreatNullAs=NullString, URL] attribute DOMString reflectedCustomURLAttr;
+    [Reflect=customContentURLAttr, URL] attribute DOMString reflectedCustomURLAttr;
+    [Reflect=customContentURLAttr, TreatNullAs=NullString, URL] attribute DOMString reflectedTreatNullAsNullStringCustomURLAttr;
+    [Reflect=customContentURLAttr, TreatNullAs=NullString, TreatUndefinedAs=NullString, URL] attribute DOMString reflectedTreatNullAsNullStringTreatUndefinedAsNullStringCustomURLAttr;
     [Reflect, ReflectOnly="unique"] attribute DOMString limitedToOnlyOneAttribute;
     [Reflect, ReflectOnly="Per"|"Paal"|"Espen"] attribute DOMString limitedToOnlyAttribute;
     [Reflect=Other, ReflectOnly="Value1"|"Value2" ] attribute DOMString limitedToOnlyOtherAttribute;