What, Why, How?

A fix for a bug where the image format’s popover goes partially offscreen because it should not do that. This just removes the placement prop so the default is used and that works better.

Testing Instructions

1. Open a post

2. Paste the following (a full width group so the image is sure to be close to the canvas edge):

   <!-- wp:group {"align":"full","layout":{"type":"default"}} -->
   <div class="wp-block-group alignfull"><!-- wp:paragraph -->
   <p><img class="wp-image-18" style="width: 150px;" src="https://placehold.co/150x150" alt=""> Let’s start this paragraph with an inline image.</p>
   <!-- /wp:paragraph --></div>
   <!-- /wp:group -->

3. Select the image so its popover appears

4. Verify the popover is not going offscreen

Screenshots or screencast

Before	After

Looking at this, I now wonder if the popover wouldn’t look better with small offset. I’ll keep this PR focused though.