Issue #1118 - Part 8: Remove no-longer-used mDidDocumentOpen and

CheckForOutdatedParent()

This was only used to check for cases when document.open() changed the
global, and elements being inserted into the document needing a new
reflector as a result.

Since document.open() no longer changes the global, this code is no
longer needed.

dom/html/nsHTMLDocument.cpp

@@ -1586,8 +1586,6 @@ nsHTMLDocument::Open(JSContext* cx,
   SetReadyStateInternal(READYSTATE_UNINITIALIZED,
                         /* updateTimingInformation = */ false);
 
-  mDidDocumentOpen = true;
-
   // Step 13 - Set our compatibility mode to standards.
   SetCompatibilityMode(eCompatibility_FullStandards);