Bug 59814 – Reduce amount of tree traversal after DOM manipulation

• Status: RESOLVED
• Resolution: WONTFIX
• Component: DOM

[Roland Steiner]

After an operation that manipulates the DOM (node insertion or removal), we traverse the affected subtree twice: Once for setTreeScope/DocumentRecursively, and once for insertedInto/removedFromDocument/Tree(). We should be able to combine the updates into a single traversal.

Note that this applies to DOM manipulation outside of shadow DOM as well, but shadow DOM exacerbates the problem.

[Dominic Cooney]

This will be too complicated because the insertedInto/removedFromDocument/Tree callbacks will need to deal with TreeScope state that is not globally consistent.