Keep Flutter.framework binaries writable so they can be code signed (#40174)

packages/flutter_tools/bin/xcode_backend.sh

@@ -142,11 +142,13 @@ BuildApp() {
     mkdir "${derived_dir}/engine"
     RunCommand cp -r -- "${flutter_podspec}" "${derived_dir}/engine"
     RunCommand cp -r -- "${flutter_framework}" "${derived_dir}/engine"
-    RunCommand find "${derived_dir}/engine/Flutter.framework" -type f -exec chmod a-w "{}" \;
+    # Make headers, plists, and modulemap files read-only to discourage editing.
+    RunCommand find "${derived_dir}/engine/Flutter.framework" -type f \( -name '*.h' -o -name '*.modulemap' -o -name '*.plist' \) -exec chmod a-w "{}" \;
   else
     RunCommand rm -rf -- "${derived_dir}/Flutter.framework"
     RunCommand cp -r -- "${flutter_framework}" "${derived_dir}"
-    RunCommand find "${derived_dir}/Flutter.framework" -type f -exec chmod a-w "{}" \;
+    # Make headers, plists, and modulemap files read-only to discourage editing.
+    RunCommand find "${derived_dir}/Flutter.framework" -type f \( -name '*.h' -o -name '*.modulemap' -o -name '*.plist' \) -exec chmod a-w "{}" \;
   fi
 
   RunCommand pushd "${project_path}" > /dev/null