This is done by no longer forwarding compositor-bound messages through
SystemFontService and making `FontContext` non-generic:
- Messages from the `FontContext` to the `Compositor` no longer need to be
forwarded through the `SystemFontService`. Instead send these messages
directly through the script IPC channel to the `Compositor`.
- Instead of adding a mock `SystemFontServiceProxy`, simply implement a
mock `SystemFontService` on the other side of an IPC channel in the
`font_context` unit test. This allows making `FontContext`
non-generic, greatly simplifying the code. The extra complexity moves
into the unit test.
These changes necessitate adding a new kind of `FontIdentifier`,
`FontIdentifier::Mock` due to the fact that local fonts have
platform-specific identifiers. This avoids having to pretend like the
system font service can have web fonts -- which was always a bit of a
hack.
These two changes are combined into one PR because they both require
extensive and similar chages in the font_context unit test which
dependended on the details of both of them.
Signed-off-by: Martin Robinson <mrobinson@igalia.com>
ac567645a7