chore: remove unused hash function (#41884)

Unused since e1e73fa #24115

Co-authored-by: trop[bot] <37223003+trop[bot]@users.noreply.github.com>
Co-authored-by: Charles Kerr <charles@charleskerr.com>

shell/common/api/electron_api_v8_util.cc

@@ -5,7 +5,6 @@
 #include <iterator>
 #include <utility>
 
-#include "base/hash/hash.h"
 #include "base/run_loop.h"
 #include "electron/buildflags/buildflags.h"
 #include "shell/common/api/electron_api_key_weak_map.h"
@@ -17,18 +16,6 @@
 #include "url/origin.h"
 #include "v8/include/v8-profiler.h"
 
-namespace std {
-
-// The hash function used by DoubleIDWeakMap.
-template <typename Type1, typename Type2>
-struct hash<std::pair<Type1, Type2>> {
-  std::size_t operator()(std::pair<Type1, Type2> value) const {
-    return base::HashInts(base::Hash(value.first), value.second);
-  }
-};
-
-}  // namespace std
-
 namespace gin {
 
 template <typename Type1, typename Type2>