Fix virtual/override/final usage in Source/platform/.

Source/platform/PODIntervalTree.h

Index: Source/platform/PODIntervalTree.h
diff --git a/Source/platform/PODIntervalTree.h b/Source/platform/PODIntervalTree.h
index 5a2f462b06ab3b74bb086c491d5fe251ba5a24f2..5f970e80295f846663ef2a2cfe19000f99025306 100644
--- a/Source/platform/PODIntervalTree.h
+++ b/Source/platform/PODIntervalTree.h
@@ -131,7 +131,7 @@ public:
         return IntervalType(low, high, data);
     }
 
-    virtual bool checkInvariants() const override
+    bool checkInvariants() const override
     {
         if (!PODRedBlackTree<IntervalType>::checkInvariants())
             return false;
@@ -181,7 +181,7 @@ private:
             searchForOverlapsFrom<AdapterType>(node->right(), adapter);
     }
 
-    virtual bool updateNode(IntervalNode* node) override
+    bool updateNode(IntervalNode* node) override
     {
         // Would use const T&, but need to reassign this reference in this
         // function.