Rich Text: Non-selected inline boundaries wrongly highlighted

[aduth]

Describe the bug

When applying an inline format to a region of text, any other texts in the same paragraph with that same format appear as highlighted. I would only expect the selected text to be highlighted.

To Reproduce

Steps to reproduce the behavior:

1. Navigate to Posts > Add New
2. Insert a new paragraph block
3. Insert some text
4. Apply bold to a fragment of text
5. Apply bold to an entirely separate fragment of text
6. Observe that both fragments of text are highlighted

Expected behavior

Only the text selected at step 5 should appear as highlighted when bold is applied.

Screenshots

Desktop

• OS: macOS Mojave Version 10.14.3
• Browser: Chrome Version 72.0.3626.119 (Official Build) (64-bit)

Additional context

Gutenberg master (e0adbe0), 5.1.0 latest release.

cc @iseulde

[ellatrix]

This is a result of having the same reference at those indices after applying the format (and normalising formats). We should probably only normalise neighbouring formats only. This used to be the case before one of the list rewrites. I can look into this after #13948, when list formats are separated.

The highlighting of other boundaries will go away as soon as you move selection, because create uses a reference per DOM element.