Sky: different tack for custom Rect type in the Canvas API.

sky/engine/bindings/BUILD.gn

 # Copyright 2015 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("//sky/engine/bindings/bindings.gni")
 import("//sky/engine/core/core.gni")
 
 source_set("bindings") {
   sources = [
     "builtin.cc",
@@ skipping 312 matching lines @@
     "--generate-globals",
     rebase_path(bindings_output_dir, root_build_dir),
     rebase_path(file_list, root_build_dir),
   ]
 
   deps = [
     ":compile_idls",
   ]
 }
 
+copy("copy_core_dart_files") {
+  sources = core_dart_files
+  outputs = [
+    "$bindings_output_dir/{{source_file_part}}",
+  ]
+}
+
 action("generate_dart_sky") {
-  sources = core_idl_files
+  sources = core_idl_files + core_dart_files
   script = "$bindings_scripts_dir/compiler.py"
 
   file_list = "$target_gen_dir/${target_name}_file_list.txt"
   write_file(file_list, rebase_path(sources, root_build_dir))
 
   inputs =
       sources + idl_compiler_files + [ "scripts/templates/dart_blink.template" ]
 
   outputs = [
     file_list,
     "$bindings_output_dir/dart_sky.dart",
   ]
 
   args = [
     "--output-directory",
     rebase_path(bindings_output_dir, root_build_dir),
     "--generate-dart-blink",
     rebase_path(bindings_output_dir, root_build_dir),
     rebase_path(file_list, root_build_dir),
   ]
 
   deps = [
+    ":copy_core_dart_files",
     ":compile_idls",
   ]
 }
 
 source_set("generated_bindings") {
   deps = [
     "//base",
     "//dart/runtime/bin:libdart_withcore",
     "//gpu/command_buffer/client:gles2_c_lib",
     "//mojo/application",
@@ skipping 19 matching lines @@
   ]
 
   include_dirs = [
     "..",
     "$root_build_dir",
   ]
 
   sources = get_target_outputs(":compile_idls")
   sources += get_target_outputs(":generate_dart_globals")
 }