Upgrade to atom-shell@0.19.2

Changelog:

* Add `plugins` attribute for `<webview>`
* Add `preload` attribute for `<webview>`
* Add `httpreferrer` attribute for `<webview>`
* Add `crashRepoter.getLastCrashReport` API
* Add `original-fs` module
* Add `preload` option for BrowserWindow
* Add APIs to toggle menu bar for BrowserWindow
* Fix wrong string when using `Buffer` for WebKit’s external string

__Linux__

* Use system window frame for undocked devtools

__Windows__

* Upload PDB files to symbol server
* Use native frame for `BrowserWindow` when DWM is off
* Fix setting default path for file dialogs

__Windows & Linux__

* Fix crash when showing error dialog on early initialization stage
* Make `auto-hide-menu-bar` work when number lock is on