backspace on Emoji does not remove whole grapheme cluster

[eliyap]

Context: Using "long" emoji like 🇺🇸 (Flags) or 🏄🏼‍♂️ (skin tone + gender modifier)

Input: pressing the Backspace key

Observed Behavior: removes one "character" at a time, leading fragments like 🇺

Expected Behavior: whole emoji should be removed

Tested on

• CM6 demo at https://codemirror.net/6/
• Google Chrome Version 91.0.4472.106 (Official Build) (x86_64)

[marijnh]

This was intentional behavior, but on closer look it indeed seems that other editors don't work like that, so attached patch drops it.

[marijnh]

Where attached patch is codemirror/commands@05812d8