Esc to exit insert mode in embeds

[mrmr1993]

This enables esc to exit insert mode for <embed>/<object> elements.

Test page here.

Ping @smblott-github

[smblott-github]

Merged into post-1.46 with a comment indicating "experimental": 99d784f. Should make it's way into master in a week or two.

@mrmr1993. Note: I'm also track of what's in post-1.46 but not in master with the in-post-1.46 label. So we can find all this stuff again if need be.

Closing.