Fix Media & Text block crash

[geriux]

Fixes #1650

Gutenberg PR -> WordPress/gutenberg#18907

To test:

• Open the Gutenberg Web editor:
• Create a new post with this code:

<!-- wp:media-text {"mediaId":29,"mediaType":"image","imageFill":true,"focalPoint":{"x":0.52,"y":0.12}} -->
<div class="wp-block-media-text alignwide is-stacked-on-mobile is-image-fill"><figure class="wp-block-media-text__media" style="background-image:url(https://geriuxx-atomic-site-1.blog/wp-content/uploads/2019/12/img_0004-1.jpg);background-position:52% 12%"><img src="https://geriuxx-atomic-site-1.blog/wp-content/uploads/2019/12/img_0004-1.jpg" alt="" class="wp-image-29"/></figure><div class="wp-block-media-text__content"><!-- wp:paragraph {"placeholder":"Content…","fontSize":"large"} -->
<p class="has-large-font-size"></p>
<!-- /wp:paragraph --></div></div>
<!-- /wp:media-text -->

• Save
• Open the newly created post from the Main Apps with metro running.
• Expect the Media & Text block to be visible without any crashes.

I'm sharing the snippet to test because there's a bug in the web editor that makes the block invalid when the setting Crop image to fill entire column is turned on, due to rounding issues. It has been fixed in master already WordPress/gutenberg#18765 but it is not on production yet.

• If there are user facing changes, I have added an item to RELEASE-NOTES.txt.

[mkevins]

This fixes the issue as described. I tested with the steps described here: #1650 (comment). Nice work @geriux 🎉 LGTM after resolving conflicts.