Revert "GL: track enabled vertex arrays as a count rather than a mask"

This reverts commit 288d041c64322fafc77cfaf23907180ebad933a1.

Reason for revert: GL errors.

Original change's description:
> GL: track enabled vertex arrays as a count rather than a mask
> 
> Bug: skia:
> Change-Id: I46ba29cb32960a415ee1993a7b957ec49c0c56d3
> Reviewed-on: https://skia-review.googlesource.com/15520
> Commit-Queue: Chris Dalton <csmartdalton@google.com>
> Reviewed-by: Brian Salomon <bsalomon@google.com>
> 

TBR=egdaniel@google.com,bsalomon@google.com,csmartdalton@google.com
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true

Change-Id: I63b0fd3c6f36326a13bf853d13ce8d28869a32cf
Reviewed-on: https://skia-review.googlesource.com/15625
Reviewed-by: Chris Dalton <csmartdalton@google.com>
Commit-Queue: Chris Dalton <csmartdalton@google.com>
3 files changed