Add initial support for v8_target_arch == "arm" to GN config

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.
 
 # Because standalone V8 builds are not supported, assume this is part of a
 # Chromium build.
 import("//build/module_args/v8.gni")
 
 # TODO(jochen): These will need to be user-settable to support standalone V8
 # builds.
@@ skipping 78 matching lines @@
     defines += [ "V8_USE_EXTERNAL_STARTUP_DATA" ]
   }
 }
 
 config("toolchain") {
   visibility = [ ":*" ]  # Only targets in this file can depend on this.
 
   defines = []
   cflags = []
 
-  # TODO(jochen): Add support for arm, mips, mipsel.
+  # TODO(jochen): Add support for arm subarchs, mips, mipsel.
 
+  if (v8_target_arch == "arm") {
+    defines += [ "V8_TARGET_ARCH_ARM" ]
+    if (arm_verson == 7) {
+      defines += [ "CAN_USE_ARMV7_INSTRUCTIONS" ]
+    }
+    if (arm_fpu == "vfpv3-d16") {
+      defines += [ "CAN_USE_VFP3_INSTRUCTIONS" ]
+    }
+    if (arm_fpu == "vfpv3") {
+      defines += [
+        "CAN_USE_VFP3_INSTRUCTIONS",
+        "CAN_USE_VFP32DREGS",
+      ]
+    }
+    if (arm_fpu == "neon") {
+      defines += [
+        "CAN_USE_VFP3_INSTRUCTIONS",
+        "CAN_USE_VFP32DREGS",
+        "CAN_USE_NEON",
+      ]
+    }
+
+    # TODO(jochen): Add support for arm_test_noprobe.
+
+    # TODO(jochen): Add support for cpu_arch != v8_target_arch/
+  }
   if (v8_target_arch == "arm64") {
     defines += [ "V8_TARGET_ARCH_ARM64" ]
   }
   if (v8_target_arch == "x86") {
     defines += [ "V8_TARGET_ARCH_IA32" ]
   }
   if (v8_target_arch == "x64") {
     defines += [ "V8_TARGET_ARCH_X64" ]
   }
   if (is_win) {
@@ skipping 1418 matching lines @@
       sources += [
         "src/d8-debug.cc",
         "$target_gen_dir/d8-js.cc",
       ]
     }
     if (v8_enable_i18n_support) {
       deps += [ "//third_party/icu" ]
     }
   }
 }