:bug: Fix regression in indent-guide in React editor

Previously the indent guide was always showing on the whitespace only
lines in the React editor. This is the same behavior as in the old
editor and had the same fix, just ported to `LinesComponent`.

See: 314833bbac33bdb7c45594550d8d10559dd2de9c

Fixes #2274
Add failing test for #2274

Tested first on a branch off of `master` to ensure that it would
actually fail :grinning:
Merge pull request #2950 from lee-dohm/ld-bug-2274

:bug: Fix regression in indent-guide in React editor