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

Source/platform/testing/ArenaTestHelpers.h

Index: Source/platform/testing/ArenaTestHelpers.h
diff --git a/Source/platform/testing/ArenaTestHelpers.h b/Source/platform/testing/ArenaTestHelpers.h
index 19d3b81c483a8a7b64ce56b6284e78b8b4ee12f2..ad473626f5a9fd62c8363bd8050503f1ac3eaa07 100644
--- a/Source/platform/testing/ArenaTestHelpers.h
+++ b/Source/platform/testing/ArenaTestHelpers.h
@@ -44,14 +44,14 @@ public:
         return adoptRef(new TrackedAllocator);
     }
 
-    virtual void* allocate(size_t size) override
+    void* allocate(size_t size) override
     {
         void* result = PODArena::FastMallocAllocator::allocate(size);
         m_allocatedRegions.append(result);
         return result;
     }
 
-    virtual void free(void* ptr) override
+    void free(void* ptr) override
     {
         size_t slot = m_allocatedRegions.find(ptr);
         ASSERT_NE(slot, kNotFound);