Add basic unit tests for `is_plugin_active()` and `is_plugin_inactive()`.

Props voldemortensen.
Fixes #30489.

git-svn-id: https://develop.svn.wordpress.org/trunk@30557 602fd350-edb4-49c9-b593-d223f7449a82
TinyMCE: use the actual image node when calculating the position of the toolbar. Fixes a bug in old IE. See #30147.

git-svn-id: https://develop.svn.wordpress.org/trunk@30558 602fd350-edb4-49c9-b593-d223f7449a82