Add a new v8_inspector target

sky/engine/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("config.gni")
 if (is_clang) {
   import("//build/config/clang/clang.gni")
 }
 if (is_posix) {
   import("//build/config/gcc/gcc_version.gni")
@@ skipping 55 matching lines @@
 
 # The follow configs apply to all targets except for unit tests, which rely on
 # static initializers.
 config("non_test_config") {
   cflags = []
 
   if (is_clang) {
     cflags += [ "-Wglobal-constructors" ]
   }
 }
+
+group("engine") {
+  deps = [
+    "//sky/engine/public:sky_headers",
+    "//sky/engine/web",
+    "//sky/engine/platform",
+    "//sky/engine/v8_inspector",
+  ]
+}