style: Simplify if statements

[Richienb]

In this PR, I simplified the IF statements by removing the curcly braces and removing the indent.

In other words, I turned this:

if (process.platform !== 'darwin') {
  app.quit()
}

into this:

if (process.platform !== 'darwin') app.quit()

[ckerr]

electron-quick-start follows standard js, so this PR looks fine. Thanks for the patch!