Gitmodules: Remove unused androidx_browser. Also use commit hash for third_party/wayland. Bug: chromium:1421776 Change-Id: I406b875e65c42413c4841227ce32035f6c004f78 Reviewed-on: https://chromium-review.googlesource.com/c/angle/angle/+/4753352 Commit-Queue: Yuxin Hu <yuxinhu@google.com> Reviewed-by: Yuxin Hu <yuxinhu@google.com>