Removing a signed/unsigned mismatch warning triggered in MSVC 11.

git-svn-id: https://llvm.org/svn/llvm-project/cfe/trunk@174986 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/lib/Format/TokenAnnotator.cpp b/lib/Format/TokenAnnotator.cpp
index 80089de..1e59561 100644
--- a/lib/Format/TokenAnnotator.cpp
+++ b/lib/Format/TokenAnnotator.cpp
@@ -729,7 +729,7 @@
       // found, insert fake parenthesis and return.
       if (Current == NULL || Current->is(tok::semi) || closesScope(*Current) ||
           ((Current->Type == TT_BinaryOperator || Current->is(tok::comma)) &&
-           getPrecedence(*Current) < Precedence)) {
+           getPrecedence(*Current) < static_cast<prec::Level>(Precedence))) {
         if (OperatorFound) {
           ++Start->FakeLParens;
           if (Current != NULL)