Optimizations around escape analysis. With tests.

Optimizations around escape analysis. With tests.

Details:
(1) added new intrinsics
(2) implemented optimizations
      more !can be null information
      more null check removals
      replace return-this uses with incoming parameter
      remove dead StringBuffer/Builder calls (with escape analysis)
(3) Fixed exposed bug in CanBeMoved()

Performance gain:
This improves CafeineString by about 360%
(removes null check from first loop, eliminates second loop completely)

Test: test-art-host

Change-Id: Iaf16a1b9cab6a7386f43d71c6b51dd59600e81c1