Delete the v8_target_cpu/v8_current_cpu hack in the GN build.

build/toolchain/gcc_toolchain.gni

 # Copyright (c) 2013 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 import("//build/config/clang/clang.gni")
 import("//build/config/nacl/config.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 import("//build/config/v8_target_cpu.gni")
 import("//build/toolchain/cc_wrapper.gni")
 import("//build/toolchain/goma.gni")
@@ skipping 457 matching lines @@
       }
       if (defined(invoker.use_sysroot)) {
         use_sysroot = invoker.use_sysroot
       }
       if (defined(invoker.v8_toolchain_cpu)) {
         v8_current_cpu = invoker.v8_toolchain_cpu
       } else {
         v8_current_cpu = current_cpu
       }
 
-      # TODO(crbug.com/625353) - Delete after v8 has been updated
-      # to only refer to v8_current_cpu. Until then, we need to make
-      # sure that v8_current_cpu always has the same value as v8_target_cpu,
-      # so that //build defines evaluate the way v8 is expecting them to.
-      v8_current_cpu = v8_target_cpu
-
       # Disable sanitizers for non-default toolchains.
       is_asan = false
       is_cfi = false
       is_lsan = false
       is_msan = false
       is_syzyasan = false
       is_tsan = false
       is_ubsan = false
       is_ubsan_null = false
       is_ubsan_no_recover = false
@@ skipping 49 matching lines @@
                              "toolchain_os",
                              "use_gold",
                              "v8_toolchain_cpu",
                            ])
 
     if (defined(invoker.use_debug_fission)) {
       use_debug_fission = invoker.use_debug_fission
     }
   }
 }