Sema: handle typo correction with ARC'ed objc properties

We would previously assert in findCapturingExpr when performing a typo
correction resulting in an assignment of an ObjC property with a strong lifetype
specifier due to the expression not being rooted in the file (invalid SLoc)
during the retain cycle check on the typo-corrected expression.  Handle the
expression type appropriately during the TreeTransform to ensure that we have a
source location associated with the expression.

Fixes PR26486.

llvm-svn: 260016
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index 32aa5a6..3083a1f 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -6586,6 +6586,10 @@
 
   ExprResult TransformBlockExpr(BlockExpr *E) { return Owned(E); }
 
+  ExprResult TransformObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
+    return Owned(E);
+  }
+
   ExprResult Transform(Expr *E) {
     ExprResult Res;
     while (true) {