added DeleteElementTxn and DeleteRangeTxn, and added merging of text insertions.

added some better error checking on all transactions.


git-svn-id: svn://10.0.0.236/trunk@17740 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/editor/libeditor/base/ChangeAttributeTxn.cpp

@@ -94,6 +94,8 @@ nsresult ChangeAttributeTxn::GetIsTransient(PRBool *aIsTransient)
 
 nsresult ChangeAttributeTxn::Merge(PRBool *aDidMerge, nsITransaction *aTransaction)
 {
+  if (nsnull!=aDidMerge)
+    *aDidMerge=PR_FALSE;
   return NS_OK;
 }