Right now, the layer tree provided by InspectorLayerTreeAgent::getLayerTree() only lists layer ids, but not the id of the layer's associated node. In order to get that id, the front-end needs to call InspectorLayerTreeAgent::nodeIdForLayerId(). However, the frequency of "layerTreeDidChange" events might be high enough that the resulting calls to getLayerTree() and subsequent calls to nodeIdForLayerId() would have the unexpected impacts of obtaining the node ids for layers that were reported too long ago and the layer tree has already changed significantly. We should let getLayerTree() report node IDs in the returned object without pushing the nodes to the front-end. That way the front-end will be able to use that information without having to request information from the backend with the latency involved.
<rdar://problem/13239602>
Closing this since the bigger changes I plan to make in https://bugs.webkit.org/show_bug.cgi?id=110407 encompass this task.