Bug 987285 - 'Let nsBaseHashtable and subclasses call MarkImmutable'. r=bsmedberg.

xpcom/glue/nsBaseHashtable.h

@@ -271,6 +271,10 @@ public:
                                             mallocSizeOf);
   }
 
+#ifdef DEBUG
+  using nsTHashtable<EntryType>::MarkImmutable;
+#endif
+
 protected:
   /**
    * used internally during EnumerateRead.  Allocated on the stack.