Removed ScrollingCoordinator and a bunch of composited scrolling'

sky/engine/platform/graphics/CompositingReasons.h

Index: sky/engine/platform/graphics/CompositingReasons.h
diff --git a/sky/engine/platform/graphics/CompositingReasons.h b/sky/engine/platform/graphics/CompositingReasons.h
index e54ba9fa6623356f00594ced84abb8b8307a63aa..d8b44a87bee1f451e5252ad96f3d105427a80ac6 100644
--- a/sky/engine/platform/graphics/CompositingReasons.h
+++ b/sky/engine/platform/graphics/CompositingReasons.h
@@ -51,7 +51,7 @@ const uint64_t CompositingReasonBlendingWithCompositedDescendants        = UINT6
 const uint64_t CompositingReasonClipsCompositingDescendants              = UINT64_C(1) << 34;
 const uint64_t CompositingReasonPerspectiveWith3DDescendants             = UINT64_C(1) << 35;
 const uint64_t CompositingReasonPreserve3DWith3DDescendants              = UINT64_C(1) << 36;
-const uint64_t CompositingReasonIsolateCompositedDescendants             = UINT64_C(1) << 38;
+const uint64_t CompositingReasoWnIsolateCompositedDescendants             = UINT64_C(1) << 38;
 
 // The root layer is a special case that may be forced to be a layer, but also it needs to be
 // a layer if anything else in the subtree is composited.
@@ -61,19 +61,17 @@ const uint64_t CompositingReasonRoot                                     = UINT6
 const uint64_t CompositingReasonLayerForAncestorClip                     = UINT64_C(1) << 40;
 const uint64_t CompositingReasonLayerForDescendantClip                   = UINT64_C(1) << 41;
 const uint64_t CompositingReasonLayerForPerspective                      = UINT64_C(1) << 42;
-const uint64_t CompositingReasonLayerForHorizontalScrollbar              = UINT64_C(1) << 43;
-const uint64_t CompositingReasonLayerForVerticalScrollbar                = UINT64_C(1) << 44;
+// FIXME(sky): 43 is unused.
+// FIXME(sky): 44 is unused.
 const uint64_t CompositingReasonLayerForOverflowControlsHost             = UINT64_C(1) << 45;
 // FIXME(sky): 46 is unused.
-const uint64_t CompositingReasonLayerForScrollingContents                = UINT64_C(1) << 47;
-const uint64_t CompositingReasonLayerForScrollingContainer               = UINT64_C(1) << 48;
 const uint64_t CompositingReasonLayerForSquashingContents                = UINT64_C(1) << 49;
 const uint64_t CompositingReasonLayerForSquashingContainer               = UINT64_C(1) << 50;
 const uint64_t CompositingReasonLayerForForeground                       = UINT64_C(1) << 51;
 const uint64_t CompositingReasonLayerForBackground                       = UINT64_C(1) << 52;
 const uint64_t CompositingReasonLayerForMask                             = UINT64_C(1) << 53;
 const uint64_t CompositingReasonLayerForClippingMask                     = UINT64_C(1) << 54;
-const uint64_t CompositingReasonLayerForScrollingBlockSelection          = UINT64_C(1) << 55;
+// FIXME(sky): 55 is unused.
 
 // Composited elements with inline transforms trigger assumed overlap so that
 // we can update their transforms quickly.