Fix compile error from r62953.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@62959 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/Expr.cpp b/lib/AST/Expr.cpp
index defb0c3..63484d1 100644
--- a/lib/AST/Expr.cpp
+++ b/lib/AST/Expr.cpp
@@ -733,7 +733,8 @@
       return cast<CastExpr>(this)->getSubExpr()->isConstantInitializer(Ctx);
     break;
   case DesignatedInitExprClass:
-    return cast<DesignatedInitExpr>(Init)->getInit()->isConstantInitializer(Ctx);
+    return cast<DesignatedInitExpr>(this)->
+            getInit()->isConstantInitializer(Ctx);
   }
 
   return isEvaluatable(Ctx);