Support Windows in incremental_build.sh (flutter#2989)

Allow running incremental_build.sh on Windows under Git Bash. Longer
term this script should be re-written in Dart (#64025), but for now this
allows running the script on Windows bots.

Author: stuartmorgan-g

script/incremental_build.sh

@@ -6,6 +6,12 @@ readonly REPO_DIR="$(dirname "$SCRIPT_DIR")"
 
 source "$SCRIPT_DIR/common.sh"
 
+if [ "$(expr substr $(uname -s) 1 5)" == "MINGW" ]; then
+  PUB=pub.bat
+else
+  PUB=pub
+fi
+
 # Plugins that deliberately use their own analysis_options.yaml.
 #
 # This list should only be deleted from, never added to. This only exists
@@ -37,19 +43,19 @@ PLUGIN_SHARDING=($PLUGIN_SHARDING)
 
 if [[ "${BRANCH_NAME}" == "master" ]]; then
   echo "Running for all packages"
-  (cd "$REPO_DIR" && pub global run flutter_plugin_tools "${ACTIONS[@]}" ${PLUGIN_SHARDING[@]})
+  (cd "$REPO_DIR" && $PUB global run flutter_plugin_tools "${ACTIONS[@]}" ${PLUGIN_SHARDING[@]})
 else
   # Sets CHANGED_PACKAGES
   check_changed_packages
 
   if [[ "$CHANGED_PACKAGES" == "" ]]; then
     echo "No changes detected in packages."
     echo "Running for all packages"
-    (cd "$REPO_DIR" && pub global run flutter_plugin_tools "${ACTIONS[@]}" ${PLUGIN_SHARDING[@]})
+    (cd "$REPO_DIR" && $PUB global run flutter_plugin_tools "${ACTIONS[@]}" ${PLUGIN_SHARDING[@]})
   else
     echo running "${ACTIONS[@]}"
-    (cd "$REPO_DIR" && pub global run flutter_plugin_tools "${ACTIONS[@]}" --plugins="$CHANGED_PACKAGES" ${PLUGIN_SHARDING[@]})
+    (cd "$REPO_DIR" && $PUB global run flutter_plugin_tools "${ACTIONS[@]}" --plugins="$CHANGED_PACKAGES" ${PLUGIN_SHARDING[@]})
     echo "Running version check for changed packages"
-    (cd "$REPO_DIR" && pub global run flutter_plugin_tools version-check --base_sha="$(get_branch_base_sha)")
+    (cd "$REPO_DIR" && $PUB global run flutter_plugin_tools version-check --base_sha="$(get_branch_base_sha)")
   fi
 fi