* Revert "Initial integration of libtxt with Flutter alongside Blink. (#3771)"
This reverts commit c548c65b5020653087b63f1f156741a1f95b5117.
* Revert "Call Selection.removeSelection if the framework has cleared the selection (#3782)"
This reverts commit e5b79ba63b92aa0c4299836f4433ec0de23b7cb3.
* Revert "Update switches to use StringView. (#3781)"
This reverts commit 07d4357b1ac4c7aa8c13f1627071e43096ef3cc5.
* Namespaces have been updated to reflect the move from //flutter/sky/shell to //flutter/shell.
* shell/BUILD.gn file has been split into smaller GN files for each subcomponent of the shell (common, GPU, diagnostic, testing).
* GN dependencies have been rewritten to stop exposing common shell dependencies as public. Duplicates have also been removed.
* GPU subcomponent has been updated make it more suitable for Vulkan integration.
* The GLFW backend has been resurrected.
