Add unittests to keep InstanceType lists in sync

src/ast/ast-types.cc

Index: src/ast/ast-types.cc
diff --git a/src/ast/ast-types.cc b/src/ast/ast-types.cc
index 8e1cca20301a9a0e59929c4c84531cd5e7207e44..55354a6019dad862648027d838ce22f4c51b1cd4 100644
--- a/src/ast/ast-types.cc
+++ b/src/ast/ast-types.cc
@@ -303,8 +303,6 @@ AstType::bitset AstBitsetType::Lub(i::Map* map) {
     case PROMISE_REACTION_JOB_INFO_TYPE:
     case FUNCTION_TEMPLATE_INFO_TYPE:
     case OBJECT_TEMPLATE_INFO_TYPE:
-    case SIGNATURE_INFO_TYPE:
-    case TYPE_SWITCH_INFO_TYPE:
     case ALLOCATION_MEMENTO_TYPE:
     case TYPE_FEEDBACK_INFO_TYPE:
     case ALIASED_ARGUMENTS_ENTRY_TYPE: