Drop UniqueId from include/v8.h

include/v8.h

Index: include/v8.h
diff --git a/include/v8.h b/include/v8.h
index b5f40c176d3ff95d5c23553012c411b2fb190134..ead6efa42c8dd2cce53616df84e86a02136280e0 100644
--- a/include/v8.h
+++ b/include/v8.h
@@ -155,30 +155,6 @@ class GlobalHandles;
 }  // namespace internal
 
 
-/**
- * General purpose unique identifier.
- */
-class UniqueId {
- public:
-  explicit UniqueId(intptr_t data)
-      : data_(data) {}
-
-  bool operator==(const UniqueId& other) const {
-    return data_ == other.data_;
-  }
-
-  bool operator!=(const UniqueId& other) const {
-    return data_ != other.data_;
-  }
-
-  bool operator<(const UniqueId& other) const {
-    return data_ < other.data_;
-  }
-
- private:
-  intptr_t data_;
-};
-
 // --- Handles ---
 
 #define TYPE_CHECK(T, S)                                       \