Roll external/skia 073073e4a..49fd5d5b7 (6 commits)
https://skia.googlesource.com/skia.git/+log/073073e4a..49fd5d5b7
2017-08-03 liyuqian@google.com Disable Delta AA for MSVC for now
2017-08-03 brianosman@google.com Add support for object creation/snapshot/deletion events
2017-08-03 mtklein@chromium.org same 16->8 bit packing trick for SSE2/SSE4.1
2017-08-03 brianosman@google.com Add missing newline to initial DM output
2017-08-03 mtklein@chromium.org Store float and byte constant colors.
2017-08-03 mtklein@chromium.org funnel all constant colors through append_constant_color()
Test: Presubmit checks will test this change.
Change-Id: Ifc1bc8334e027386695143bf8fede8aefd5378a9