Thanks uses an outdated PNG for an icon graphic. It also has issues with alignment.
Let's modernise this to an SVG to avoid this problem.
Acceptance criteria
- Use mw-ui-icon for generating the icon
- Update icon to new asset
- Remove CSS code in MobileFrontend that workarounds the lack of usage of mw-ui-icon
QA steps
General QA of the thanks on diff feature - make sure you are happy with the icon and the behaviour.
- Login and visit a diff e.g. https://en.m.wikipedia.beta.wmflabs.org/wiki/Special:MobileDiff/81611 or https://en.m.wikipedia.beta.wmflabs.org/wiki/Special:MobileDiff/381373
- Thank the user