Webgl renderer does not render when writing if a selection exists

[Tyriar]

Repro:

1. Open demo
2. Make a selection
3. Run in console: term.write('foo')

[jeanp413]

Created a PR #3232 fixing this if it's of any help

Also found this issue, happens in canvas or webgl renderer:

1. Open demo
2. Run in console: term.write('foo')
3. Resize terminal rows or columns
4. 🐛 Observe text foo disappears

Should I create a separate issue?