fix decorate bug (#4277) without adding extra layers of render tree

[jaked]

Description
The combination of #4152 and #4138 broke decoration in Editable: the decorate function is not called on immediate children of the editor (because the function is retrieved from a React context before the context is set).

I fixed this in #4394 by adding a wrapper component around each child in useChildren, so the context is set by the time we retrieve the decorate function.

But after some discussion with @ulion (on #4277 and #4394) I think it's better not to wrap every child, but only the immediate children of Editable; this achieves the same thing without adding extra layers to the render tree. And since the immediate children of Editable are not passed to renderLeaf, it's not necessary to wrap them individually for #4152. So this change reverts the changes to use-children.tsx from #4394, and adds back a Children component in Editable in order to defer the call to useDecorate.

Issue
Fixes: #4277

Example
See test—decorate is called on all children of editor.

Context
As above, the issue is that a React context (added in #4138) is used before being set (because #4152 replaced the Children component with a call to useChildren). In order to fix the bug without defeating the goals of these two changes, we wrap a Children component around the useChildren call in Editable to defer the use of the context.

Checks

• The new code matches the existing patterns and styles.
• The tests pass with yarn test.
• The linter passes with yarn lint. (Fix errors with yarn fix.)
• The relevant examples still work. (Run examples with yarn start.)
• You've added a changeset if changing functionality. (Add one with yarn changeset add.) No changeset needed; no functionality is affected by this change.

[changeset-bot]

🦋 Changeset detected

Latest commit: 6aaf329

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 2 packages

Name	Type
slate-react	Patch
slate	Patch

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[dylans]

thanks, I thought a changeset was not needed because no functionality was changed.

My opinion is that something did change which makes it easier to track down regressions, but I could argue it either way. :)