Update D8 and R8 to 2.1.8-dev

Version: master 2.1.8-dev
This build IS NOT suitable for preview or public release.

Built here: go/r8-releases/raw/2.1.8-dev

Test: TARGET_PRODUCT=aosp_arm64 m -j core-oj
Change-Id: I75fee9de5e52bb30d63f796584f60cafc099375f
2 files changed