Remove dead code from DartController

sky/engine/core/core.gni

 # 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.
 
 sky_core_output_dir = "$root_gen_dir/sky/core"
 
 sky_core_files = [
   "Init.cpp",
   "Init.h",
   "animation/ActiveAnimations.cpp",
@@ skipping 968 matching lines @@
   "rendering/style/StyleTransformData.cpp",
   "rendering/style/StyleTransformData.h",
   "rendering/style/StyleVisualData.cpp",
   "rendering/style/StyleVisualData.h",
   "rendering/style/StyleWillChangeData.cpp",
   "rendering/style/StyleWillChangeData.h",
   "script/dart_controller.cc",
   "script/dart_controller.h",
   "script/dart_debugger.cc",
   "script/dart_debugger.h",
-  "script/dart_library_provider_webview.cc",
-  "script/dart_library_provider_webview.h",
   "script/dart_service_isolate.cc",
   "script/dart_service_isolate.h",
   "script/dom_dart_state.cc",
   "script/dom_dart_state.h",
   "script/monitor.h",
   "view/BeginFrameCallback.h",
   "view/EventCallback.h",
   "view/View.cpp",
   "view/View.h",
 ]
@@ skipping 128 matching lines @@
                                        "events/HashChangeEvent.idl",
                                        "events/KeyboardEvent.idl",
                                        "events/PageTransitionEvent.idl",
                                        "events/PointerEvent.idl",
                                        "events/TextEvent.idl",
                                        "events/TransitionEvent.idl",
                                        "events/UIEvent.idl",
                                        "events/WheelEvent.idl",
                                      ],
                                      "abspath")