Improve ArraySet codegen.

Simplify the reference case to emit fewer instructions and
take at most one branch in the main path.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Test: aosp_taimen-userdebug boots.
Test: testrunner.py --target --optimizing
Bug: 32489401
Change-Id: I9d76b7795ec01e6245ed3184cd8d384389e5070d
4 files changed