winaccessibility: clear entires from XHWNDDocList too

... in DeleteAccObj().  Otherwise pointers to deleted documents will be
used.

Change-Id: Ia807dc3a2c782019cf7fc874d264058219956d74

winaccessibility/source/service/AccObjectWinManager.cxx

@@ -557,6 +557,10 @@ void AccObjectWinManager::DeleteAccObj( XAccessible* pXAcc )
     size_t i = XResIdAccList.erase(accObj.GetResID());
     assert(i != 0);
     DeleteFromHwndXAcc(pXAcc);
+    if (DOCUMENT == accObj.GetRole())
+    {
+        XHWNDDocList.erase(accObj.GetParentHWND());
+    }
     XIdAccList.erase(pXAcc); // note: this invalidates accObj so do it last!
 }