Revert of Revert of Add gpu support for Apple specific 'Vertex Arrays' functions...

Revert of Revert of Add gpu support for Apple specific 'Vertex Arrays' functions (patchset #1 id:1 of https://codereview.chromium.org/750973003/)

Reason for revert:
Original patchset seems to have been exonerated. Crash was mac-specific, but appears to be triggered by a non-mac-specific change (https://codereview.chromium.org/747043004/); suspecting driver bug?

Original issue's description:
> Revert of Add gpu support for Apple specific 'Vertex Arrays' functions (patchset #2 id:20001 of https://codereview.chromium.org/754653002/)
>
> Reason for revert:
> Suspected in DM crashes, e.g.
>
> 2033 tasks left	 344M peak	  843ms	tabl-cuteoverload_skp
> Signal 11:
> _sigtramp (+0x1a)
> create_surface(CanvasConfig const&, GrContext*) (+0x1b2)
> test_WritePixels(skiatest::Reporter*, GrContextFactory*) (+0x8d4)
> skiatest::WritePixelsClass::onRun(skiatest::Reporter*) (+0x21)
> skiatest::Test::run() (+0x7c)
> DM::GpuTestTask::draw(GrContextFactory*) (+0x8c)
> DM::GpuTask::run(GrContextFactory*) (+0xa6)
> DM::TaskRunner::wait() (+0x7f)
> dm_main() (+0x33f)
> main (+0x27)
>
>
> On all MacMini platforms (the following URL with -Mac{10.6,10.7,10.8}- and -{Debug,Release}):
>
> http://build.chromium.org/p/client.skia/builders/Test-Mac10.6-MacMini4.1-GeForce320M-x86_64-Debug
>
>
> Original issue's description:
> > Add gpu support for Apple specific 'Vertex Arrays' functions
> >
> > BUG=skia:
> >
> > Committed: https://skia.googlesource.com/skia/+/af000f469e1b0153ce445c96ca3d20e6d12224cc
>
> TBR=bsalomon@google.com,paraboul@gmail.com
> NOTREECHECKS=true
> NOTRY=true
> BUG=skia:
>
> Committed: https://skia.googlesource.com/skia/+/55fe3d7748b873e362edc4e6a43bd77914ed25fb

TBR=bsalomon@google.com,paraboul@gmail.com
NOTREECHECKS=true
NOTRY=true
BUG=skia:

Review URL: https://codereview.chromium.org/734633005