Make more [TreatNullAs=NullString] DOMString arguments nullable

Source/core/dom/Document.idl

Index: Source/core/dom/Document.idl
diff --git a/Source/core/dom/Document.idl b/Source/core/dom/Document.idl
index 46fec3bf92259e905f80e67af41732479596e1d6..6dedbc9982428254cb06363e31fe60188ffdcde1 100644
--- a/Source/core/dom/Document.idl
+++ b/Source/core/dom/Document.idl
@@ -98,7 +98,7 @@ typedef (CanvasRenderingContext2D or WebGLRenderingContext) RenderingContext;
     [CustomElementCallbacks]
     boolean            execCommand([Default=Undefined] optional DOMString command,
                                    [Default=Undefined] optional boolean userInterface,
-                                   [TreatNullAs=NullString, TreatUndefinedAs=NullString,Default=Undefined] optional DOMString value);
+                                   [TreatUndefinedAs=NullString, Default=Undefined] optional DOMString? value);

[Jens Widell, 2014/07/02 12:42:20]

If we fix http://crbug.com/335871, then in terms of behavior, this could just be
"optional DOMString? value = null". (CG would differ somewhat, though.)

The same probably goes for various arguments touched in this CL that don't have
[Default=Undefined], but in those cases it depends on how the C++ side is
implemented.

[haraken, 2014/07/02 12:50:27]

Yeah, it's worth fixing.

 
     boolean            queryCommandEnabled([Default=Undefined] optional DOMString command);
     boolean            queryCommandIndeterm([Default=Undefined] optional DOMString command);