Fix image cropped vertically

[etoledom]

Fixes #444

Gutenberg side: WordPress/gutenberg#13096

The image size implementations tries to follow closely the web implementation. I tried to share some code from ImageSize but most of it is platform specific. I made a small utils to share some math calculations.

On a future PR I plan to implement some kind of loading indicator.
cc @iamthomasbishop

To test:

• Run the example project.
• Scroll down to the last block.
• Check that the image displays correctly as shown in the attached image.

[iamthomasbishop]

Awesome! Thanks for fixing this @etoledom!!

[etoledom]

Hey @iamthomasbishop - glad you like it :)

I'm wandering what do you think about an activity indicator when the image is loading?
This is how it looks now:

(That is pretty much the behavior on web, but on mobile I would expect some kind of activity indicator)

[iamthomasbishop]

I would also expect a loading indicator. Is there any chance we can utilize the same approach that we took on Aztec uploads, where you see a loader over the top of the media as it loads?

[etoledom]

I created a new issue for the activity indicator task.
Let's move that conversation to: #451

[etoledom]

Hey @Tug !
I updated the gutenberg reference to latest master. Everything is working in my local tests.
Please take a look before the final merge.
Thank you!

[etoledom]

The gutenberg reference already was updated in develop so this PR is not needed anymore.