Add pkg:smith as a dependency for flutter_frontend_server.

[aam]

For all packages that depend on dart-sdk internal pkg:expect package add pkg:smith.

This is needed to roll dart past dart-lang/sdk@b453c6b which added pkg:smith as a dependency to pkg:expect.

Here is where dart->engine roller stumbles at the moment:

The roller failed to create a CL with:
Command exited with exit status 2: DEPOT_TOOLS_UPDATE=0 HOME=/home/skia LUCI_CONTEXT=/data/tmp/luci_context.170844833 PATH=/data/depot_tools:/cipd:/cipd/cipd_bin_packages:/cipd/cipd_bin_packages/bin:/cipd/cipd_bin_packages/cpython:/cipd/cipd_bin_packages/cpython/bin:/cipd/cipd_bin_packages/cpython3:/cipd/cipd_bin_packages/cpython3/bin:/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin SKIP_GCE_AUTH_FOR_GIT=1 python /data/depot_tools/gclient.py sync --delete_unversioned_trees --force; Stdout+Stderr:
________ running 'python3 src/tools/remove_stale_pyc_files.py src/tools' in '/data'
________ running 'python3 src/build/linux/sysroot_scripts/install-sysroot.py --arch=x64' in '/data'
________ running 'python3 src/build/linux/sysroot_scripts/install-sysroot.py --arch=arm64' in '/data'
________ running 'python3 src/flutter/tools/pub_get_offline.py' in '/data'
'/data/src/third_party/dart/tools/sdks/dart-sdk/bin/pub get --offline' failed in 'src/flutter/flutter_frontend_server' with status 69:
b'Resolving dependencies...\nBecause every version of expect from path depends on smith any which is forbidden, expect from path is forbidden.\nSo, because flutter_frontend_server depends on expect from path, version solving failed.\n'
Error: Command 'python3 src/flutter/tools/pub_get_offline.py' returned non-zero exit status 1 in /data
'/data/src/third_party/dart/tools/sdks/dart-sdk/bin/pub get --offline' failed in 'src/flutter/flutter_frontend_server' with status 69:
b'Resolving dependencies...\nBecause every version of expect from path depends on smith any which is forbidden, expect from path is forbidden.\nSo, because flutter_frontend_server depends on expect from path, version solving failed.\n'

. At deps_local.go:73 deps_local.go:83 deps_local.go:138 git_common.go:158 git_checkout.go:74 autoroller.go:485 autoroller.go:442 state_machine.go:284 state_machine.go:53 state_machine.go:168 state_machine.go:839 state_machine.go:852 state_machine.go:858 autoroller.go:777 autoroller.go:336 util.go:391 cleanup.go:57 asm_amd64.s:1371