Remove context menus.

sky/engine/core/core.gni

Index: sky/engine/core/core.gni
diff --git a/sky/engine/core/core.gni b/sky/engine/core/core.gni
index 5edb13b3367cf5d84cc5fdac68d88b655b0a7c6a..b1e19fc447a4a31d418738ad28fff47cd99d6d7d 100644
--- a/sky/engine/core/core.gni
+++ b/sky/engine/core/core.gni
@@ -656,8 +656,6 @@ sky_core_files = [
   "events/PopStateEvent.h",
   "events/ProgressEvent.cpp",
   "events/ProgressEvent.h",
-  "events/RelatedEvent.cpp",
-  "events/RelatedEvent.h",
   "events/ResourceProgressEvent.cpp",
   "events/ResourceProgressEvent.h",
   "events/ScopedEventQueue.cpp",
@@ -1021,8 +1019,6 @@ sky_core_files = [
   "page/AutoscrollController.cpp",
   "page/AutoscrollController.h",
   "page/Chrome.cpp",
-  "page/ContextMenuController.cpp",
-  "page/ContextMenuProvider.h",
   "page/EventHandler.cpp",
   "page/EventWithHitTestResults.h",
   "page/FocusController.cpp",
@@ -1291,7 +1287,6 @@ core_idl_files = get_path_info([
   "events/PageTransitionEvent.idl",
   "events/PopStateEvent.idl",
   "events/ProgressEvent.idl",
-  "events/RelatedEvent.idl",
   "events/ResourceProgressEvent.idl",
   "events/TextEvent.idl",
   "events/TouchEvent.idl",
@@ -1409,7 +1404,6 @@ core_event_idl_files = get_path_info([
   "events/PageTransitionEvent.idl",
   "events/PopStateEvent.idl",
   "events/ProgressEvent.idl",
-  "events/RelatedEvent.idl",
   "events/ResourceProgressEvent.idl",
   "events/TextEvent.idl",
   "events/TouchEvent.idl",