fix #25573, add option to disable implicit dynamic

pkg/analyzer/lib/src/context/context.dart

Index: pkg/analyzer/lib/src/context/context.dart
diff --git a/pkg/analyzer/lib/src/context/context.dart b/pkg/analyzer/lib/src/context/context.dart
index dd0e0ee7d929d9737cbd2c311d59c9bb0e696d61..627a4bb815589c79978cfec525edac06fcc27240 100644
--- a/pkg/analyzer/lib/src/context/context.dart
+++ b/pkg/analyzer/lib/src/context/context.dart
@@ -281,6 +281,9 @@ class AnalysisContextImpl implements InternalAnalysisContext {
         ((options is AnalysisOptionsImpl)
             ? this._options.implicitCasts != options.implicitCasts
             : false) ||
+        ((options is AnalysisOptionsImpl)
+            ? this._options.implicitDynamic != options.implicitDynamic
+            : false) ||
         this._options.enableStrictCallChecks !=
             options.enableStrictCallChecks ||
         this._options.enableGenericMethods != options.enableGenericMethods ||
@@ -312,6 +315,7 @@ class AnalysisContextImpl implements InternalAnalysisContext {
     if (options is AnalysisOptionsImpl) {
       this._options.strongModeHints = options.strongModeHints;
       this._options.implicitCasts = options.implicitCasts;
+      this._options.implicitDynamic = options.implicitDynamic;
     }
     if (needsRecompute) {
       for (WorkManager workManager in workManagers) {