Consistently use only one of virtual/OVERRIDE/FINAL.

src/d8.cc

Index: src/d8.cc
diff --git a/src/d8.cc b/src/d8.cc
index 44a4a81e32c65f7781403b9e148e971e0259360c..653e36694d0c8d9bd94c7e3baaf3c8af3433f08a 100644
--- a/src/d8.cc
+++ b/src/d8.cc
@@ -1539,15 +1539,9 @@ class ShellArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
 
 class MockArrayBufferAllocator : public v8::ArrayBuffer::Allocator {
  public:
-  virtual void* Allocate(size_t) OVERRIDE {
-    return malloc(0);
-  }
-  virtual void* AllocateUninitialized(size_t length) OVERRIDE {
-    return malloc(0);
-  }
-  virtual void Free(void* p, size_t) OVERRIDE {
-    free(p);
-  }
+  void* Allocate(size_t) OVERRIDE { return malloc(0); }
+  void* AllocateUninitialized(size_t length) OVERRIDE { return malloc(0); }
+  void Free(void* p, size_t) OVERRIDE { free(p); }
 };