Handling tabs during text shaping caused issues because we tried to
index 'input_glyph_info' whilst iterating until 'glyph_count' and these
can be different sizes.
The difference is due to when one or more characters get
merged into the same glyph when calling 'input_glyph_info' (see
https://lazka.github.io/pgi-docs/HarfBuzz-0.0/classes/glyph_info_t.html).
We don't want to render tabs as they come up as tofu characters so
instead let's strip them out of the text chunk before starting text
shaping.
2534e7aeff