Twenty Fourteen: Use HTML5 comment markup

[obenland]

Eventually we should move to completely support the core HTML5. Let's start with the comment markup.

[lancewillett]

@obenland Can you refresh this patch? The CSS didn't apply cleanly.

[obenland]

Refreshed patch.

While ready for commit, Takashi still needs to decide on how to deal with the reply link.

[lancewillett]

In 25087:

Twenty Fourteen: Use HTML5 comment markup, props obenland. Fixes #25045.

[Jayjdk]

The URL input type needs styling. Patch attached.

[Jayjdk]

Add url to the list of input selectors

[iamtakashi]

Style adjustments for the new HTML5 comment markup. And minor bug fixes for comment responsive pattern.

[lancewillett]

In 25216:

Twenty Fourteen: style adjustments for the new HTML5 comment markup, and minor bug fixes for comment responsive pattern. Props iamtakashi, fixes #25045.