[base] Remove base::is_same

Use C++17's std::conjunction together with std::is_same instead.

R=leszeks@chromium.org

Bug: v8:12425
Change-Id: I75a973f14f0642b00d390aa6ab4eb1ce0208c074
Reviewed-on: https://chromium-review.googlesource.com/c/v8/v8/+/3568478Reviewed-by: Leszek Swirski <leszeks@chromium.org>
Commit-Queue: Clemens Backes <clemensb@chromium.org>
Cr-Commit-Position: refs/heads/main@{#79848}

src/base/template-utils.h

@@ -60,16 +60,6 @@ struct has_output_operator<
     T, TStream, decltype(void(std::declval<TStream&>() << std::declval<T>()))>
     : std::true_type {};
 
-// {is_same<Ts...>::value} is true if all Ts are the same, false otherwise.
-template <typename... Ts>
-struct is_same : public std::false_type {};
-template <>
-struct is_same<> : public std::true_type {};
-template <typename T>
-struct is_same<T> : public std::true_type {};
-template <typename T, typename... Ts>
-struct is_same<T, T, Ts...> : public is_same<T, Ts...> {};
-
 }  // namespace base
 }  // namespace v8
 

src/codegen/register.h

@@ -22,9 +22,9 @@ constexpr bool ShouldPadArguments(int argument_count) {
 #ifdef DEBUG
 template <typename... RegTypes,
           // All arguments must be either Register or DoubleRegister.
-          typename = typename std::enable_if<
-              base::is_same<Register, RegTypes...>::value ||
-              base::is_same<DoubleRegister, RegTypes...>::value>::type>
+          typename = typename std::enable_if_t<
+              std::conjunction_v<std::is_same<Register, RegTypes>...> ||
+              std::conjunction_v<std::is_same<DoubleRegister, RegTypes>...>>>
 inline constexpr bool AreAliased(RegTypes... regs) {
   int num_different_regs = RegListBase{regs...}.Count();
   int num_given_regs = (... + (regs.is_valid() ? 1 : 0));