Comment tweak I forgot to bug mrbkap about.

js/src/jsstr.c

@@ -362,7 +362,10 @@ js_str_escape(JSContext *cx, JSObject *obj, uintN argc, jsval *argv, jsval *rval
             newlength += 5; /* The character will be encoded as %uXXXX */
         }
 
-        /* NB: this works because newlength can be incremented by at most 5. */ 
+        /*
+         * This overflow test works because newlength is incremented by at
+         * most 5 on each iteration.
+         */
         if (newlength < length) {
             JS_ReportOutOfMemory(cx);
             return JS_FALSE;