Support captioned images with CKEditor's Enhanced Image widget

Support was recently for CKEditor's Enhanced Image widget in #2715393: Error while putting a link on an image..

However, if the image is "captioned", the only thing that gets linked is the caption, not the image. Here's the before/after HTML.

Before:

<figure class="image">
<img alt="" height="225" src="/sites/default/files/img_0224.jpg" width="300" />
<figcaption>Caption</figcaption>
</figure>

After:

<figure class="image">
<img alt="" height="225" src="/sites/default/files/img_0224.jpg" width="300" />
<figcaption><a href="/node/1">Caption</a></figcaption>
</figure>

What I expected:

<figure class="image">
<a href="/"><img alt="" height="225" src="/sites/default/files/img_0224.jpg" width="300" /></a>
<figcaption>Caption</figcaption>
</figure>