Fix icon size regression

[jasmussen]

This PR fixes an icon size regression that was introduced in #9828. Basically SVG icons are between 20 and 24px.

If an SVG has an explicit width, it uses that width, within the boundaries of those extremes. But unfortunately it also means if the SVG doesn't have an explicit width or height, it collapses to the min-width and min-height.

This PR updates documentation, and adds explicit dimensions for all block icons used.

Before:

After:

[chrisvanpatten]

@jasmussen I think this is actually another issue. In the BlockIcon component, we should be enforcing width="24" and height="24" if those attributes aren't provided:

https://github.com/WordPress/gutenberg/blob/master/packages/editor/src/components/block-icon/index.js#L24-L25

I'm inclined to think this is related to all the React Native-related SVG refactoring… cc @gziolo

That said I think it's good for this to land either way — better to be explicit about width/height if possible because it encourages users to do the same!

[chrisvanpatten]

Approving for the explicitness of providing width/height (I think it's good for us to be explicit) but we should still look into why the default width/height attributes aren't being applied inside <BlockIcon />.

[jasmussen]

In the BlockIcon component, we should be enforcing width="24" and height="24" if those attributes aren't provided:

I really like the sound of that, and I'd like to do that in this branch. Let me see if I can.

[jasmussen]

Boy that's a gnarly rebase. Something big just changed with embeds that moved it all elsewhere. I might do a complete re-do of this one. Apologies if that requires an extra ping.

[jasmussen]

Interesting, from a casual dive into the BlockIcon component, it looks like it should, as Chris suggests, output explicit widths and heights on each icon, according to https://github.com/WordPress/gutenberg/blob/master/packages/editor/src/components/block-icon/index.js#L25. @gziolo you are stronger than me in code, can you figure out why those attributes aren't properly output?

[chrisvanpatten]

@jasmussen Sorry yes that was slightly confusingly worded — I meant that it should already be enforcing that 24 default 😄

There was a lot of work done around the move to the React Native-friendly version of the SVG component so my guess is that it's connected to that work.

Also instead of a rebase you could probably just do git checkout master packages/block-library/src/embed/index.js which should bring the master version of the embed file back into this branch, and then you can commit this and open a new PR for the embeds.

[jasmussen]

Closing this in favor of #10987.