This fixes a couple presubmit issues when running on Windows:
* check_gn didn't properly normalize paths
* eslint didn't execute in node successfully since the bin style for the
npm install was unix specific (it's a CMD file on Windows)
Bug: 929919
Change-Id: Iec7e1057254047bd0a6539e16df964dc8a58d528
Reviewed-on: https://chromium-review.googlesource.com/c/1459576
Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Jeff Fisher <jeffish@microsoft.com>
Cr-Original-Commit-Position: refs/heads/master@{#633810}
Cr-Mirrored-From: https://chromium.googlesource.com/chromium/src
Cr-Mirrored-Commit: d2dcac5ced285df053bc094b8e36d80a998f0079