Add the initial TypoExpr AST node for delayed typo correction.

llvm-svn: 220692
diff --git a/clang/lib/AST/ItaniumMangle.cpp b/clang/lib/AST/ItaniumMangle.cpp
index 7666467..e41c664 100644
--- a/clang/lib/AST/ItaniumMangle.cpp
+++ b/clang/lib/AST/ItaniumMangle.cpp
@@ -2627,6 +2627,7 @@
   case Expr::ParenListExprClass:
   case Expr::LambdaExprClass:
   case Expr::MSPropertyRefExprClass:
+  case Expr::TypoExprClass:  // This should no longer exist in the AST by now.
     llvm_unreachable("unexpected statement kind");
 
   // FIXME: invent manglings for all these.