Support index.js module resolution at startup of Electron.

atom/browser/lib/init.coffee

@@ -92,5 +92,8 @@ app.setAppPath packagePath
 # Load the chrome extension support.
 require './chrome-extension'
 
+# Set main startup script of the app.
+mainStartupScript = packageJson.main or 'index.js'
+
 # Finally load app's main.js and transfer control to C++.
-Module._load path.join(packagePath, packageJson.main), Module, true
+Module._load path.join(packagePath, mainStartupScript), Module, true

docs/tutorial/quick-start.md

@@ -67,6 +67,9 @@ like this:
 }
 ```
 
+__Note__: If the `main` field is not present in `package.json`, Electron will
+attempt to load an `index.js`.
+
 The `main.js` should create windows and handle system events, a typical
 example being: