Create a new expression class, CXXThisExpr, to handle the C++ 'this' primary expression. Remove CXXThis from PredefinedExpr

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@58695 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/AST/ExprCXX.cpp b/lib/AST/ExprCXX.cpp
index 82626d8..0eead3c 100644
--- a/lib/AST/ExprCXX.cpp
+++ b/lib/AST/ExprCXX.cpp
@@ -33,6 +33,10 @@
   return child_iterator();
 }
 
+// CXXThisExpr
+Stmt::child_iterator CXXThisExpr::child_begin() { return child_iterator(); }
+Stmt::child_iterator CXXThisExpr::child_end() { return child_iterator(); }
+
 // CXXThrowExpr
 Stmt::child_iterator CXXThrowExpr::child_begin() { return &Op; }
 Stmt::child_iterator CXXThrowExpr::child_end() {