[BUG] Can't edit Header Content in Header block

[jjsanderson]

Describe the bug
In the editor, I'm unable to select and edit the (Header Content) placeholder.

To Reproduce

1. Add Header block
2. Attempt to edit (Header Content)
3. Fail.

Platform (please complete the following information):

• OS X 10.14
• Safari 12.1

Additional context
Well, whaddayaknow... the block works as expected in Chrome. Huh. Looks like #26 is only partly resolved, but we can maybe chalk it up to (another) Safari weirdness?

[jaymcp]

Thanks for the report, @jjsanderson. I may have to rework how this block works in order to resolve this issue permanently. I'll add it to my list :)

[jjsanderson]

This also seem to apply to the link text elements in Benenson's Image block.