Fix StringChange for optimizing compiler.

Uses optimizing compiler more and fixes x86_64 invoke codegen.

Bug: 21902634

(cherry-picked from commit e0a9a53ec4b4ccbf9b1d67957fb99a45b469ccc2)

Change-Id: I56881889bee7092b8401b090af1c0f1004c11667
2 files changed