Run LSA as a part of the LSE pass.

Make LSA a helper class, not an optimization pass. Move all
its allocations to ScopedArenaAllocator to reduce the peak
memory usage a little bit.

Test: m test-art-host-gtest
Test: testrunner.py --host --optimizing
Change-Id: I7fc634abe732d22c99005921ffecac5207bcf05f
10 files changed