Compile V8 with extra optimization in GN Release mode.

BUILD.gn

 # Copyright 2014 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.
 
 # TODO(jochen): These will need to be user-settable to support standalone V8
 # builds.
 v8_compress_startup_data = "off"
 v8_deprecation_warnings = false
 v8_enable_disassembler = false
 v8_enable_gdbjit = false
@@ skipping 1108 matching lines @@
       "src/ic/mips64/ic-mips64.cc",
       "src/ic/mips64/ic-compiler-mips64.cc",
       "src/ic/mips64/stub-cache-mips64.cc",
     ]
   }
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [ ":internal_config", ":features", ":toolchain" ]
 
+  if (!is_debug) {
+    configs -= [ "//build/config/compiler:optimize" ]
+    configs += [ "//build/config/compiler:optimize_max" ]
+  }
+
   defines = []
   deps = [ ":v8_libbase" ]
 
   if (is_win) {
     # TODO(jschuh): crbug.com/167187 fix size_t to int truncations.
     cflags = [ "/wd4267" ]
   }
   if (is_linux) {
     if (v8_compress_startup_data == "bz2") {
       libs += [ "bz2" ]
@@ skipping 65 matching lines @@
     "src/base/sys-info.cc",
     "src/base/sys-info.h",
     "src/base/utils/random-number-generator.cc",
     "src/base/utils/random-number-generator.h",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [ ":internal_config_base", ":features", ":toolchain" ]
 
+  if (!is_debug) {
+    configs -= [ "//build/config/compiler:optimize" ]
+    configs += [ "//build/config/compiler:optimize_max" ]
+  }
+
   defines = []
 
   if (is_posix) {
     sources += [
       "src/base/platform/platform-posix.cc"
     ]
   }
 
   if (is_linux) {
     sources += [
@@ skipping 43 matching lines @@
     "src/libplatform/task-queue.cc",
     "src/libplatform/task-queue.h",
     "src/libplatform/worker-thread.cc",
     "src/libplatform/worker-thread.h",
   ]
 
   configs -= [ "//build/config/compiler:chromium_code" ]
   configs += [ "//build/config/compiler:no_chromium_code" ]
   configs += [ ":internal_config_base", ":features", ":toolchain" ]
 
+  if (!is_debug) {
+    configs -= [ "//build/config/compiler:optimize" ]
+    configs += [ "//build/config/compiler:optimize_max" ]
+  }
+
   deps = [
     ":v8_libbase",
   ]
 }
 
 ###############################################################################
 # Executables
 #
 
 if (current_toolchain == host_toolchain) {
@@ skipping 77 matching lines @@
     deps = [
       ":v8_base",
       ":v8_nosnapshot",
     ]
   }
 
   direct_dependent_configs = [ ":external_config" ]
 }
 
 }