Make indirect-conversion graph for Profiler UIs, and Profilers

[mhansen]

Include conversions. Maybe have a tab, just like we did on Profiles, to show the bigger graph.

There's a lot of graph traversal going on. I wonder if we could generalise this, with some kind of walk function that can decide whether to walk backwards or forwards, and whether to follow conversions or not. Probably time to generalise some of this code.

[mhansen]

Probably a lot of people start with a profiler, and would be interested in intermediate transforms that you can run on the (possibly many) outputs of the profiler.