Media: Ensure imgareaselect.js is not initialized twice for the same image....

Media: Ensure imgareaselect.js is not initialized twice for the same image. May happen when uploading an image into a post and then clicking on Edit Image.

Fixes #49262.
Built from https://develop.svn.wordpress.org/trunk@47229


git-svn-id: https://core.svn.wordpress.org/trunk@47029 1a063a9b-81f0-0310-95a4-ce76da25c4cd