enable lint prefer_equal_for_default_values (#18156)

diff --git a/packages/flutter_tools/lib/src/ios/mac.dart b/packages/flutter_tools/lib/src/ios/mac.dart
index c4c1453..3d49c80 100644
--- a/packages/flutter_tools/lib/src/ios/mac.dart
+++ b/packages/flutter_tools/lib/src/ios/mac.dart
@@ -190,8 +190,8 @@
   BuildInfo buildInfo,
   String targetOverride,
   bool buildForDevice,
-  bool codesign: true,
-  bool usesTerminalUi: true,
+  bool codesign = true,
+  bool usesTerminalUi = true,
 }) async {
   if (!await upgradePbxProjWithFlutterAssets(app.name, app.appDirectory))
     return new XcodeBuildResult(success: false);