Replace build5-a3 with vm255-m3
Replace build5-a3 with vm255-m3

TBR=rmistry
BUG=chromium:513325,skia:4107

Review URL: https://codereview.chromium.org/1257683002

google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,Tiger66639/skia-buildbot,Tiger66639/skia-buildbot