Remove some unneeded DEPS from //sky

sky/engine/platform/BUILD.gn

Index: sky/engine/platform/BUILD.gn
diff --git a/sky/engine/platform/BUILD.gn b/sky/engine/platform/BUILD.gn
index 1b838bc821c6e20ad6c502fdd6c46344439f2c9c..54dc25afb7d99cedebdcb31925d45d6c3e5f4019 100644
--- a/sky/engine/platform/BUILD.gn
+++ b/sky/engine/platform/BUILD.gn
@@ -295,11 +295,6 @@ source_set("platform") {
     "geometry/TransformState.h",
     "graphics/BitmapImage.cpp",
     "graphics/BitmapImage.h",
-    "graphics/Canvas2DImageBufferSurface.h",
-    "graphics/Canvas2DLayerBridge.cpp",
-    "graphics/Canvas2DLayerBridge.h",
-    "graphics/Canvas2DLayerManager.cpp",
-    "graphics/Canvas2DLayerManager.h",
     "graphics/Color.cpp",
     "graphics/Color.h",
     "graphics/ColorSpace.cpp",
@@ -330,7 +325,6 @@ source_set("platform") {
     "graphics/GraphicsContextStateSaver.h",
     "graphics/GraphicsTypes.cpp",
     "graphics/GraphicsTypes.h",
-    "graphics/GraphicsTypes3D.h",
     "graphics/Image.cpp",
     "graphics/Image.h",
     "graphics/ImageBuffer.cpp",
@@ -420,14 +414,6 @@ source_set("platform") {
     "graphics/filters/SourceGraphic.h",
     "graphics/filters/SpotLightSource.cpp",
     "graphics/filters/SpotLightSource.h",
-    "graphics/gpu/DrawingBuffer.cpp",
-    "graphics/gpu/DrawingBuffer.h",
-    "graphics/gpu/Extensions3DUtil.cpp",
-    "graphics/gpu/Extensions3DUtil.h",
-    "graphics/gpu/WebGLImageBufferSurface.cpp",
-    "graphics/gpu/WebGLImageBufferSurface.h",
-    "graphics/gpu/WebGLImageConversion.cpp",
-    "graphics/gpu/WebGLImageConversion.h",
     "graphics/skia/GaneshUtils.cpp",
     "graphics/skia/GaneshUtils.h",
     "graphics/skia/NativeImageSkia.cpp",
@@ -584,7 +570,6 @@ source_set("platform") {
   deps = [
     ":make_platform_generated",
     "//base:base",
-    "//gpu/command_buffer/client:gles2_c_lib",
     "//mojo/application",
     "//mojo/common",
     "//mojo/environment:chromium",
@@ -606,7 +591,6 @@ source_set("platform") {
   ]
 
   forward_dependent_configs_from = [
-    "//gpu/command_buffer/client:gles2_c_lib",
     "//skia",
     "//third_party:jpeg",
     "//third_party/iccjpeg",
@@ -666,7 +650,6 @@ test("platform_unittests") {
     "geometry/RoundedRectTest.cpp",
     "graphics/GraphicsContextTest.cpp",
     "graphics/ThreadSafeDataTransportTest.cpp",
-    "graphics/gpu/DrawingBufferTest.cpp",
     "image-decoders/ImageDecoderTest.cpp",
     "mac/ScrollElasticityControllerTest.mm",
     "network/HTTPParsersTest.cpp",