js2-mode: Merge from upstream

Git commit 1c53de75e0acd19d61ad45a91b32c183948e5128
* packages/auctex/tex-jp.el: Add coding cookie.
Put coding cookie in elisp header line.
js2-mode: Merge from upstream

Git commit 714dca50644c75884d9d90f10328c7a12e02cdcc