Roll external/skia 243ed3755..76fcb10f4 (5 commits)
https://skia.googlesource.com/skia.git/+log/243ed3755..76fcb10f4
2017-05-05 msarett@google.com Fix clang compiler error in SkSLFileOutputStream
2017-05-05 borenet@google.com Presubmit: ensure empty line between CL title and description
2017-05-05 csmartdalton@google.com Revert "GL: track enabled vertex arrays as a count rather than a mask"
2017-05-05 reed@google.com speed-up 4f version of modecolorfilter and modulate
2017-05-05 msarett@google.com Add support for row-by-row png encodes
Test: Presubmit checks will test this change.
Change-Id: I876da14ca61057eea7a64704996b72892f6c0372