Compatibility shims - Mozilla | MDN

To help developers migrate their extensions to multiprocess Firefox we're implementing a number of compatibility shims that in many cases will mean extensions continue to function in multiprocess Firefox without needing any updates. For example: whenever extensions try to access web content, the browser will return a Cross Process Object Wrapper that gives the chrome code synchronous access to the

[Rockridge]

MozillaはFirefoxをマルチプロセス化するにあたり、アドオンの互換性を保つためのライブラリ（shim）を用意している。ただし、一時的な措置だ。参照：http://en.wikipedia.org/wiki/Shim_%28computing%29