Queries the system list of user-preferred languages, and sends it to the
engine just after starting it up, as well as after any OS locale change.

macOS portion of https://github.com/flutter/flutter/issues/45152

See: b/163653659

* Delete CSS paint code

This reverts commit 8d08e6c3.

The test handler wasn't replying, which logged an error message during
the unit test.

Fixes https://github.com/flutter/flutter/issues/62560

Fixes https://github.com/flutter/flutter/issues/53399

* Roll Harfbuzz to 2.7.0 c6ca30dc757ff86416d97d358f20080b979b80c9 (HAVE_PTHREAD)

* memory-manage images and shaders

__has_feature(cxx_rtti) is a clang extension, but clients of this code
are mostly using the VS toolchain. This makes the RTTI check work with
more compilers.

This improves raster cache control from apps and enables
GPU acceleration for some offscreen workloads that would
fallback to software.

Test: PlatformViewTests.GetGrContextTest
Co-authored-by: NDavid Reveman <reveman@google.com>