Add flutter runner test build as part of CI

.cirrus.yml

@@ -75,6 +75,9 @@ task:
       compile_fuchsia_script: |
         cd $ENGINE_PATH/src
         ./flutter/tools/fuchsia/build_fuchsia_artifacts.py --engine-version HEAD --runtime-mode debug
+      build_flutter_runner_tests: |
+        cd $ENGINE_PATH/src/flutter
+        ./ci/build_flutter_runner_tests.sh
 
 # WINDOWS
 task:

ci/build_flutter_runner_tests.sh

@@ -0,0 +1,17 @@
+#!/bin/bash
+set -ex
+
+PATH="$HOME/depot_tools:$PATH"
+cd ..
+
+# Build the flutter runner tests far directory
+flutter/tools/gn --fuchsia --no-lto --runtime-mode debug
+ninja -C out/fuchsia_debug_x64 flutter/shell/platform/fuchsia/flutter:flutter_runner_tests
+
+# Generate the far package
+flutter/tools/fuchsia/gen_package.py\
+  --pm-bin $PWD/fuchsia/sdk/linux/tools/pm\
+  --package-dir $PWD/out/fuchsia_debug_x64/flutter_runner_tests_far\
+  --signing-key $PWD/flutter/tools/fuchsia/development.key\
+  --far-name flutter_runner_tests
+