Specs: Drop @nonnull from dom.md, drop ChildNode from dom.md, drop TreeRoot from dom.md, other mino…

sky/specs/events.md

Index: sky/specs/events.md
diff --git a/sky/specs/events.md b/sky/specs/events.md
index 54d869603b6b8de5004d9c6f3f505afb1a40dfa2..a38680f4bf745b82a241e3c8e6bcfee7beed1108 100644
--- a/sky/specs/events.md
+++ b/sky/specs/events.md
@@ -131,6 +131,9 @@ abstract class Event<ReturnType> {
   // TODO(ianh): abstract API for doing things at shadow tree boundaries 
   // TODO(ianh): do events get blocked at scope boundaries, e.g. focus events when both sides are in the scope?
   // TODO(ianh): do events get retargetted, e.g. focus when leaving a custom element?
+  // e.g. sent from inside a shadow tree, when exiting the shadow tree, focus event should:
+  //  - disappear if we're moving from one to another element
+  //  - be targetted if it's going to another node in a different scope
 }
 
 class EventTarget {