[regression] Preact 10.14.0 breaks selection offset on controlled text inputs

[birtles]

• Check if updating to the latest Preact version resolves the issue (it does not)

Describe the bug
A clear and concise description of what the bug is.

After upgrading to Preact 10.14.0, for controlled text inputs, the selection is reset in certain cases.

To Reproduce

Steps to reproduce the behavior:

1. Go to https://codesandbox.io/s/crazy-field-ng230t
2. Click on the text input box (after waiting for it to render)
3. Type "abc"
4. Move the cursor between "a" and "b"
5. Press Backspace

Expected behavior
What should have happened when following the steps above?

The "a" should be deleted leaving "bc" but with the text selection in front of "bc".

Actual behavior

"a" is deleted leaving "bc" but the cursor is moved to after "bc".

Tested with Firefox and Chrome on Windows. This did not happen with 10.13.2.

[marvinhagemeister]

Tracked down the source of this issue to this PR #3926 . I cannot reproduce the error without compat. Delaying the value setting in afterEvent by delaying it by another Promise tick seems to resolve it. Not sure if this is the proper fix though.

  function afterEvent(eventType, target) {
    if (target.value != null && target.value !== target._prevValue) {
-    target.value = target._prevValue;
+    Promise.resolve().then(() => target.value = target._prevValue);
    }
    if (eventType === 'change' && target.checked != null) {
      target.checked = target._prevValue;
    }
  }

cc @andrewiggins

[developit]

@marvinhagemeister waiting one tick actually seems reasonable here.