Fix typo.


git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@170904 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Format/Format.cpp b/lib/Format/Format.cpp
index fd08de5..6983f73 100644
--- a/lib/Format/Format.cpp
+++ b/lib/Format/Format.cpp
@@ -612,7 +612,7 @@
       } else if (Line.Tokens[i].Tok.is(tok::at) &&
                  Line.Tokens[i - 2].Tok.is(tok::at)) {
         // Don't put two objc's '@' on the same line. This could happen,
-        // as in, @optinal @property ...
+        // as in, @optional @property ...
         Annotation.MustBreakBefore = true;
       } else if (Line.Tokens[i].Tok.is(tok::colon)) {
         Annotation.SpaceRequiredBefore =