Parse: Token consumption modernization and loop de-nesting

Cleanup only.

llvm-svn: 198539
diff --git a/clang/lib/Parse/ParseExprCXX.cpp b/clang/lib/Parse/ParseExprCXX.cpp
index fe380e2..42e7370 100644
--- a/clang/lib/Parse/ParseExprCXX.cpp
+++ b/clang/lib/Parse/ParseExprCXX.cpp
@@ -1008,10 +1008,8 @@
 
     // Parse 'mutable'[opt].
     SourceLocation MutableLoc;
-    if (Tok.is(tok::kw_mutable)) {
-      MutableLoc = ConsumeToken();
+    if (TryConsumeToken(tok::kw_mutable, MutableLoc))
       DeclEndLoc = MutableLoc;
-    }
 
     // Parse exception-specification[opt].
     ExceptionSpecificationType ESpecType = EST_None;