Add the initial TypoExpr AST node for delayed typo correction.

llvm-svn: 220692
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 78de257..d49d9b2 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -8625,6 +8625,7 @@
   case Expr::CXXDeleteExprClass:
   case Expr::CXXPseudoDestructorExprClass:
   case Expr::UnresolvedLookupExprClass:
+  case Expr::TypoExprClass:
   case Expr::DependentScopeDeclRefExprClass:
   case Expr::CXXConstructExprClass:
   case Expr::CXXStdInitializerListExprClass: