Work around #34235 in front_end.

Change-Id: I7e5d2e63bfd018d21ff9587f178440da39a5078d
Reviewed-on: https://dart-review.googlesource.com/71232
Reviewed-by: Konstantin Shcheglov <scheglov@google.com>
Reviewed-by: Brian Wilkerson <brianwilkerson@google.com>
Commit-Queue: Paul Berry <paulberry@google.com>

pkg/front_end/lib/src/fasta/kernel/expression_generator.dart

@@ -953,7 +953,8 @@ abstract class ContextAwareGenerator implements Generator {
       {int offset: -1,
       bool voidContext: false,
       Procedure interfaceTarget,
-      bool isPreIncDec: false}) {
+      bool isPreIncDec: false,
+      bool isPostIncDec: false}) {
     return makeInvalidWrite(value);
   }