analyzer: Remove strongMode from DriverOptions

Change-Id: I4e864870c8286de84d266f9f7c04ae566edffbee
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/390666
Auto-Submit: Samuel Rawlins <srawlins@google.com>
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Commit-Queue: Konstantin Shcheglov <scheglov@google.com>
diff --git a/pkg/analyzer/lib/src/lint/analysis.dart b/pkg/analyzer/lib/src/lint/analysis.dart
index 768499b..b13cc35 100644
--- a/pkg/analyzer/lib/src/lint/analysis.dart
+++ b/pkg/analyzer/lib/src/lint/analysis.dart
@@ -53,9 +53,6 @@
 
   /// The path to a `.packages` configuration file
   String? packageConfigPath;
-
-  /// Whether to use Dart's Strong Mode analyzer.
-  bool strongMode = true;
 }
 
 /// A driver _only used_ by [DartLinter], which is only used by package:linter