Revert r155737, restoring the MaxDepth in the BalancedDelimiterTracker to 256.

r155737 turned out to be a temporary work around.  The correct fix was in r155823.

llvm-svn: 157627

clang/include/clang/Parse/Parser.h

@@ -455,7 +455,7 @@ private:
       }
     }
     
-    enum { MaxDepth = 512 };
+    enum { MaxDepth = 256 };
     
     bool diagnoseOverflow();
     bool diagnoseMissingClose();