DEPS.xwalk: Roll v8-crosswalk (5b2efea -> f2bc708)

f2bc708 Merge pull request #62 from huningxin/fix-simd-reg-deoptimizer
34478f0 [SIMD.js] Refactor the simd128 registers in deoptimizer
883f9fd Merge pull request #60 from huningxin/fix-arm64
8299b0f [SIMD.js] Fix build failure on arm64 architecture
69921d6 Merge pull request #47 from vvavrychuk/simd-mips
75c28d9 [PATCH] fixed compilation v8 on mips
Merge pull request #2666 from huningxin/roll_v8

DEPS.xwalk: Roll v8-crosswalk (5b2efea -> f2bc708)