Fix two issues in fast baseline compiler.

- Add a missing fence after allocation.
- Create a frame before fetching any register, otherwise, we may wrongly
  use a caller-saved register that can be overwritten by the hotness
  slow path.

Test: 719-varhandle-concurrency
Change-Id: I90278172e3d4f9a3561b269b35a59bd3e8ad1dfd
1 file changed