Editor: images should respect height attribute

[designsimply]

Raised by @gwwar

In the html tab of the editor we respect set width, but not height when it is the only dimension attribute set.

When clicking back to the visual tab, the following is properly sized:

<img src="http://i.imgur.com/SaxpuCP.gif" width="100" />

But this is not:

<img src="http://i.imgur.com/SaxpuCP.gif" height="100" />

HTML tab:

Visual Tab

Note from @aduth

Noting that this is consistent with the wp-admin treatment for the twenty* series of themes.

[rachelmcr]

Closing as this is not an issue in Gutenberg.

#bug-scrub #pre-gutenburg-bug-purge