Simplify hotness count in baseline compiled code.

- Always require the current ArtMethod, which also removes the need to
  handle empty frames.
- Remove the use of some temporary registers.
- Require a profiling info when compiling baseline.
- Add a slow path for requiring an optimized compilation.
- Make the counter decrement instead of increment.

A next CL will make the hotness configurable through --jittreshold.

Test: test.py
Bug: 146423102
Change-Id: I1485f66401d6ed218456fe2849eb05fa77479668
13 files changed