Currently ProfilerListener channels the code events to Processor
via CpuProfiler - we don't need this indirection and can just hook
it up directly. This also makes it easier to test because we don't need
a CpuProfiler object just to test the Processor.

Drive-by cleanup:
- Remove NUMBER_OF_TYPES from CodeEventRecord as it is not used.
- Remove Isolate* parameter from AddDeoptStack and AddCurrentStack as
  a Processor object is only ever for one Isolate. Store the Isolate*
  on the ProfilerEventsProcessor object itself.
- Remove the default case from switch in ProcessCodeEvent().

Bug: v8:5193
Change-Id: I26c1a46b0eec34b5248b707d1997c3a9409a9604
Reviewed-on: https://chromium-review.googlesource.com/c/1286341Reviewed-by: Yang Guo <yangguo@chromium.org>
Commit-Queue: Peter Marshall <petermarshall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56740}