RichText: fix backspace for IE

[ellatrix]

Description

Fixes #15945. The approach is as follows: call onInput when selection changes and then content has changed as well. Input always results in a selection change, so it's a good way to detect input in browsers that don't support the input event, such as IE.

How has this been tested?

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.

[jasmussen]

YAAAASS! You are amazing!

From purely a functional point of view, IE11 is now working as it should! So good. Thank you.

Codewise, it looks like a lot of red. Specifically it looks like it's actually REMOVING an IE fix. Does that mean the old fix was the cause of havoc?

In any case, such nice work. Thank you.

[ellatrix]

Sort of. The old fix was introduced in #6667, I've never cared enough about IE so far to have a look at it. What that fix does is mapping the textinput event to input for IE, because IE doesn't support the input event. The problem is that textinput does not fire on deletion. So that fix tries to work around it by using keyup. The problem lies somewhere there. Perhaps the old fix can be fixed, but I don't really like the fix much, I think it might be better to look at selectionchange and see if there's any content change. If there is, call the input handler. The benefit of that is also we are sure that we can update selection and content at the same time, just like the input event. I think this approach makes the most sense... and it works.

[ellatrix]

I'll wait to merge until there is a code review as well.

[jasmussen]

Forgot to attach the GIF I recorded:

[talldan]

Seems like a good improvement.