Gets the registered Globals.
array An array of globals
public function getGlobals() {
  if (null === $this->globals) {
    $this->globals = isset($this->staging['globals']) ? $this->staging['globals'] : array();
    foreach ($this
      ->getExtensions() as $extension) {
      $this->globals = array_merge($this->globals, $extension
        ->getGlobals());
    }
  }
  return $this->globals;
}