After this patch, platform messages now take the same path through the system
that semantics data does (on Android). Support on iOS will be in another patch.
This patch prepares us to switch sending semantics information over mojom to
using dart:ui directly. Currently the recorded information is dropped on the
floor, but that will improve in future patches.
The new boot sequence on Fuchsia now gives us the more accurate RGB_x888 pixel
format, which we should support. Also finish pushing pixels to the screen
before drawing new pixels.
After this patch, Flutter apps on Fuchsia can access their asset
bundles. Unlike other platforms, the asset bundles are stored in memory
rather than in the file system.
After this patch, we're able to run spinning_square on Fuchsia. I've
left some TODO comments about some shortcuts I've taken that we'll need
to improve in the future.
This patch should contain all the code we need to run Flutter on
Fuchsia's software framebuffer (without text). I haven't actually tried
running the code, so I'm sure it doesn't work yet.
