Remove Profiler::setInstance()

This is a weird construction that only existed for dumpHTML.
DumpHTML will no longer require this as of Ia38aa904.

It won't work with future plans to separate profiling & profiling
output

Change-Id: I4d7806596fa233a2b2d1d691c8adfa68724f20f5
Merge "Remove Profiler::setInstance()"