Fix paste after focus

[ellatrix]

Description

Fixes #15724.

This is a small fix for the bug that duplicates the rich text contents after pasting in a rich text instance that just received focus.

How has this been tested?

Copy a small amount of text.
Open the Gutenberg demo content.
Place the caret at the end of the first paragraph.
Move selection out of the window: e.g. place the caret in the address bar.
Place the caret again at the end of the first paragraph.
Now paste the text.
No content should be duplicated.

Screenshots

Types of changes

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.

[gziolo]

I tested the exact same action as posted in the issue and I could reproduce it on master but not in this branch. Great change 💯

I tested pasting at the beginning, in the middle and at the end of the Paragraph block. Tried also with Heading and List blocks.

[ellatrix]

I’ll attempt to create an e2e test in just a bit. Thanks for the review!

[gziolo]

I’ll attempt to create an e2e test in just a bit. Thanks for the review!

Sounds great, I merged this change as I want to play again with Puppeteer upgrade and this might (or not) help with some of the intermittent issues :)

[ellatrix]

It doesn't seem possible to me to create an e2e test for this fix.

	it.only( 'should update internal selection after fresh focus', async () => {
		await page.keyboard.press( 'Enter' );
		await page.keyboard.type( '1' );
		// Focus the address bar (move focus out of the window).
		await pressKeyWithModifier( 'primary', 'l' );
		// Focus the rich text instance again (not at the start).
		await page.click( '.wp-block-paragraph', { button: 'middle' } );
		// Should internally set bold at selection.
		await pressKeyWithModifier( 'primary', 'b' );
		// "2" should be bold.
		await page.keyboard.type( '2' );

		expect( await getEditedPostContent() ).toMatchSnapshot();
	} );

Doing this this manually fails, but in Puppeteer it succeeds. :)
Perhaps in some cases the selectionchange event is triggered, I'm not sure.

[ellatrix]

Blurring the element seems to trigger it to fail. And it succeeds with this branch. Yay!

[ellatrix]

@gziolo I doubt it will fix the intermittent failures. Puppeteer won't wait for an animation frame. Let me think about that. :D