Fix sourcemap directory organizing on Windows (facebook#2456) (facebook#2610)

* Fix sourcemap directory organizing on Windows

* Update comments

Author: pluscubed

packages/react-scripts/config/webpack.config.dev.js

@@ -77,9 +77,9 @@ module.exports = {
     chunkFilename: 'static/js/[name].chunk.js',
     // This is the URL that app is served from. We use "/" in development.
     publicPath: publicPath,
-    // Point sourcemap entries to original disk location
+    // Point sourcemap entries to original disk location (format as URL on Windows)
     devtoolModuleFilenameTemplate: info =>
-      path.resolve(info.absoluteResourcePath),
+      path.resolve(info.absoluteResourcePath).replace(/\\/g, '/'),
   },
   resolve: {
     // This allows you to set a fallback for where Webpack should look for modules.

packages/react-scripts/config/webpack.config.prod.js

@@ -75,9 +75,9 @@ module.exports = {
     chunkFilename: 'static/js/[name].[chunkhash:8].chunk.js',
     // We inferred the "public path" (such as / or /my-project) from homepage.
     publicPath: publicPath,
-    // Point sourcemap entries to original disk location
+    // Point sourcemap entries to original disk location (format as URL on Windows)
     devtoolModuleFilenameTemplate: info =>
-      path.relative(paths.appSrc, info.absoluteResourcePath),
+      path.relative(paths.appSrc, info.absoluteResourcePath).replace(/\\/g, '/'),
   },
   resolve: {
     // This allows you to set a fallback for where Webpack should look for modules.