Fix script_thaw to set its local root.

js/src/jsscript.c

@@ -725,6 +725,7 @@ script_thaw(JSContext *cx, JSObject *obj, uintN argc, jsval *argv,
     str = js_ValueToString(cx, argv[0]);
     if (!str)
         return JS_FALSE;
+    argv[0] = STRING_TO_JSVAL(str);
 
     /* create new XDR */
     xdr = JS_XDRNewMem(cx, JSXDR_DECODE);