Revert "allow both slash types"

This reverts commit 7a600416e131b33610b1c96a367b3cb2569f458e.

Reason for revert: <speculative revert; may have broken nanobench>

Original change's description:
> allow both slash types
> 
> Windows allows forwards and backwards slashes
> for path directory delimiters.
> 
> R=​halcanary@google.com
> 
> Change-Id: Ie6f1257c98ac8e2468d9297b5dc391fd17f4ae82
> Reviewed-on: https://skia-review.googlesource.com/90821
> Reviewed-by: Hal Canary <halcanary@google.com>
> Commit-Queue: Cary Clark <caryclark@google.com>

TBR=halcanary@google.com,bungeman@google.com,caryclark@google.com,caryclark@skia.org

Change-Id: If2eefdc6dbf6b7df0280b005cea12aff4b91cf09
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Reviewed-on: https://skia-review.googlesource.com/91401
Reviewed-by: Cary Clark <caryclark@google.com>
Commit-Queue: Cary Clark <caryclark@google.com>
2 files changed