objc - minor comment fix up and cleanup.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@138253 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Sema/SemaObjCProperty.cpp b/lib/Sema/SemaObjCProperty.cpp
index ddb7eeb..a5fb31a 100644
--- a/lib/Sema/SemaObjCProperty.cpp
+++ b/lib/Sema/SemaObjCProperty.cpp
@@ -144,7 +144,7 @@
                                      bool *isOverridingProperty,
                                      TypeSourceInfo *T,
                                      tok::ObjCKeywordKind MethodImplKind) {
-  ObjCCategoryDecl *CDecl = dyn_cast<ObjCCategoryDecl>(CurContext);
+  ObjCCategoryDecl *CDecl = cast<ObjCCategoryDecl>(CurContext);
   // Diagnose if this property is already in continuation class.
   DeclContext *DC = CurContext;
   IdentifierInfo *PropertyId = FD.D.getIdentifier();