TextInput: Fixed #7474, issue 3

[Alspb]

Fixed #7474, issue 3:

With a line that wraps across multiple lines or multi-line text, if you use up-arrow, it doesn't keep its position horizontally based on the pixel number offset from left, but rather based on number of characters. So with non-uniform character font, it looks weird and is different than e.g. firefox.

Maintainer merge checklist

• [ ] Title is descriptive/clear for inclusion in release notes.
• [ ] Applied a Component: xxx label.
• [ ] Applied the api-deprecation or api-break label.
• [ ] Applied the release-highlight label to be highlighted in release notes.
• [ ] Added to the milestone version it was merged into.
• [ ] Unittests are included in PR.
• [ ] Properly documented, including versionadded, versionchanged as needed.