[gn] Add unittests

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.
 
 import("//build/config/android/config.gni")
 import("//build/config/arm.gni")
 import("//build/config/mips.gni")
 import("//build/config/sanitizers/sanitizers.gni")
 
 if (is_android) {
@@ skipping 2003 matching lines @@
       "//build/config/sanitizers:deps",
       "//build/win:default_exe_manifest",
     ]
   }
 }
 
 ###############################################################################
 # Public targets
 #
 
+group("gn_all") {

[Michael Achenbach, 2016/05/25 09:12:53]

This ports parts of
https://code.google.com/p/chromium/codesearch#chromium/src/v8/gypfiles/all.gyp

Calling it like chromium does:
https://code.google.com/p/chromium/codesearch#chromium/src/BUILD.gn&l=34

+  testonly = true
+
+  deps = [
+    ":d8",
+    ":v8_shell",
+  ]
+
+  if (host_os != "mac" || !is_android) {
+    # These items don't compile for Android on Mac.
+    deps += [
+      "test/unittests:unittests",
+    ]
+  }
+}
+
 if (is_component_build) {
   component("v8") {
     sources = [
       "src/v8dll-main.cc",
     ]
 
     public_deps = [
       ":v8_base",
       snapshot_target,
     ]
@@ skipping 144 matching lines @@
   sources = [
     "test/fuzzer/wasm-asmjs.cc",
   ]
 
   deps = [
     ":fuzzer_support",
   ]
 
   configs = [ ":internal_config" ]
 }