fix over-application of `unnecessary_string_escapes`

Follow-up from: https://dart-review.googlesource.com/c/sdk/+/240905

Change-Id: I3b05a9f7cac9f58697d2feec086bc60f44285605
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/241049
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Phil Quitslund <pquitslund@google.com>
diff --git a/pkg/analyzer/test/src/task/strong/checker_test.dart b/pkg/analyzer/test/src/task/strong/checker_test.dart
index 8e78316..99c68fe 100644
--- a/pkg/analyzer/test/src/task/strong/checker_test.dart
+++ b/pkg/analyzer/test/src/task/strong/checker_test.dart
@@ -2884,15 +2884,15 @@
   }
 
   test_relaxedCasts() async {
-    await assertErrorsInCode('''
+    await assertErrorsInCode(r'''
 class A {}
 
 class L<T> {}
 class M<T> extends L<T> {}
 //     L<dynamic|Object>
-//    /              
+//    /              \
 // M<dynamic|Object>  L<A>
-//                  /
+//    \              /
 //          M<A>
 // In normal Dart, there are additional edges
 //  from M<A> to M<dynamic>
@@ -2962,10 +2962,10 @@
   }
 }
 ''', [
-      error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 764, 5),
-      error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 783, 5),
-      error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 1032, 5),
-      error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 1202, 5),
+      error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 766, 5),
+      error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 785, 5),
+      error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 1034, 5),
+      error(CompileTimeErrorCode.INVALID_ASSIGNMENT, 1204, 5),
     ]);
   }