Add analysis option that will be used to fix #26583

pkg/analyzer/test/src/task/strong/checker_test.dart

Index: pkg/analyzer/test/src/task/strong/checker_test.dart
diff --git a/pkg/analyzer/test/src/task/strong/checker_test.dart b/pkg/analyzer/test/src/task/strong/checker_test.dart
index 8a6376dac3265dc9ad457d3a986f8a4c8a7ae737..1cc677666d22d421ed1157ebf2552bbcc8b7ccf0 100644
--- a/pkg/analyzer/test/src/task/strong/checker_test.dart
+++ b/pkg/analyzer/test/src/task/strong/checker_test.dart
@@ -1900,6 +1900,13 @@ main() {
 ''');
   }
 
+  void test_implicitCasts() {
+    addFile('num n; int i = /*info:ASSIGNMENT_CAST*/n;');
+    check();
+    addFile('num n; int i = /*warning:ASSIGNMENT_CAST*/n;');
+    check(implicitCasts: false);
+  }
+
   void test_invalidOverrides_baseClassOverrideToChildInterface() {
     checkFile('''
 class A {}