Remove TODO comments, not planning to implement this

Author: cschleiden

internal/sync/context.go

@@ -206,7 +206,6 @@ func propagateCancel(parent Context, child canceler) {
 			p.children[child] = struct{}{}
 		}
 	} else {
-		// TODO: support custom context implementations with their own `Done` channel
 		panic("not implemented")
 		// go func() {
 		// 	s := NewSelector()

internal/sync/context_test.go

@@ -44,7 +44,6 @@ func TestWithCancel(t *testing.T) {
 	require.True(t, canceled)
 }
 
-// TODO: Support custom context implementations with their own `Done` channel
 // type myDoneCtx struct {
 // 	Context
 // }