Fix type of 'this' and add a decltype test.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@75291 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/DeclCXX.cpp b/lib/AST/DeclCXX.cpp
index b7051f8..45825e1 100644
--- a/lib/AST/DeclCXX.cpp
+++ b/lib/AST/DeclCXX.cpp
@@ -360,7 +360,7 @@
   else
     ClassTy = C.getTagDeclType(const_cast<CXXRecordDecl*>(getParent()));
   ClassTy = ClassTy.getWithAdditionalQualifiers(getTypeQualifiers());
-  return C.getPointerType(ClassTy).withConst();
+  return C.getPointerType(ClassTy);
 }
 
 CXXBaseOrMemberInitializer::