Don't allocate a buffer when assigning a zero-length string, just call Truncate(

) instead (bug 328755).  r=darin.


git-svn-id: svn://10.0.0.236/branches/MOZILLA_1_8_BRANCH@191369 18797224-902f-48f8-a5cc-f745e15eee43

mozilla/xpcom/string/src/nsTSubstring.cpp

@@ -287,7 +287,7 @@ void
 nsTSubstring_CharT::Assign( const char_type* data, size_type length )
   {
       // unfortunately, some callers pass null :-(
-    if (!data)
+    if (!data || length == 0)
       {
         Truncate();
         return;