Make editor p tag "go with the flow".

[m-e-h]

Description

This commit sets the p tag to inherit whatever font-size and line-height are set on the body i.e., .editor-styles-wrapper.
Currently the p tag here overrides a theme's most basic of font styles unless font-size and line-height are set on p in that theme.
And from what I've seen, being that specific on p is an uncommon pattern.

This also makes it easier and requires less specificity to style paragraphs on a per block basis by simply adding the font-size to the block container.

How has this been tested?

I see no visual changes on a fresh underscores theme with demo content.

Types of changes

Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.

[chrisvanpatten]

This should partly fix #11200, I think?

[m-e-h]

Yep, I actually tried to find that ticket @chrisvanpatten but couldn't remember what it was exactly.

Looking at it now, this wouldn't directly fix that issue. The p would still choose font-size: inherit style over the one in .has-medium-font-size.

Unless a has-medium-font-size class was on one of the wrapping elements like the <div class="editor-rich-text has-medium-font-size>.

[youknowriad]

Worth checking with themes not providing editor styles to see if it's correct. I remember that this was originally needed because Core used to styles for the paragraphs by default but maybe this inherit technique fix the issue.

[kjellr]

This seems solid, and should allow themes to be a little less specific in their style declarations. 👍

I tested with a number of themes: some that provided editor styles, and some that didn't. All seemed to work just fine.