DevTools: Fix presubmit scripts on Windows

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/1459576Reviewed-by: Dmitry Gozman <dgozman@chromium.org>
Commit-Queue: Jeff Fisher <jeffish@microsoft.com>
Cr-Commit-Position: refs/heads/master@{#633810}

third_party/blink/renderer/devtools/scripts/check_gn.js

@@ -73,7 +73,7 @@ function checkAllDevToolsFiles() {
   const errors = [];
   const excludedFiles = ['InspectorBackendCommands.js', 'SupportedCSSProperties.js', 'ARIAProperties.js'];
   const gnVariable = 'all_devtools_files';
-  const lines = selectGNLines(`${gnVariable} = [`, ']');
+  const lines = selectGNLines(`${gnVariable} = [`, ']').map(path.normalize);
   if (!lines.length) {
     return [
       'Could not identify all_devtools_files list in gn file',

third_party/blink/renderer/devtools/scripts/local_node.py

@@ -11,8 +11,7 @@ import sys
 SCRIPTS_PATH = path.dirname(path.abspath(__file__))
 THIRD_PARTY_PATH = path.join(SCRIPTS_PATH, '..', '..', '..', '..')
 NODE_PATH = path.join(THIRD_PARTY_PATH, 'node')
-ESLINT_PATH = path.join(THIRD_PARTY_PATH, 'devtools-node-modules', 'third_party',
-                        'node_modules', '.bin', 'eslint')
+ESLINT_PATH = path.join(THIRD_PARTY_PATH, 'devtools-node-modules', 'third_party', 'node_modules', 'eslint', 'bin', 'eslint.js')
 
 try:
     old_sys_path = sys.path[:]