Fix type inference of getters that "override" setters and vice versa.

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

Index: pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
diff --git a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
index c4dcf4da2c4373108dd20f6f8fcb23f2c2b6b579..4cb87f84b78dcbf55f9d2c4182bcd218a18fe967 100644
--- a/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
+++ b/pkg/front_end/lib/src/fasta/kernel/kernel_shadow_ast.dart
@@ -1278,6 +1278,13 @@ abstract class KernelMember implements Member {
     return null;
   }
 
+  static void recordCrossOverride(
+      KernelMember member, Member overriddenMember) {
+    if (member._fieldNode != null) {
+      member._fieldNode.crossOverrides.add(overriddenMember);
+    }
+  }
+
   static void recordOverride(KernelMember member, Member overriddenMember) {
     if (member._fieldNode != null) {
       member._fieldNode.overrides.add(overriddenMember);