- Add support for `text-decoration-line: double`: Line drawing is done
similar to how it works in Firefox and Chromium. A gap of half of line
thickness is added between each line.
- Fix support for `text-decoration-line: wavy`: Wavy lines rectangles
were not calcualted properly, which meant they were rendered as solid
lines. Now the amplitude of the wave is 1.5 times line thickness.
Testing: A manual test is updated `tests/html/text_deco_simple.html`
to cover more cases. In general, rendering of text-decorations is
difficult
to test via reftesting.
Fixes#17887.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>