Maximizable Dialog make the main window's scrollbar disappear

[nwkyom]

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Plunkr Case (Bug Reports)
Test directly on the PrimeNG site: https://www.primefaces.org/primeng/#/dialog

Current behavior
The vertical scrollbar of the current page disappeared after maximizing a dialog.

Expected behavior
The vertical scrollbar still must be displayed.

Minimal reproduction of the problem with instructions
Check the vertical window's scrollbar is displayed !
Open the dialog, maximize it and close it.
=> There is no more scrollbar on the current page.

What is the motivation / use case for changing the behavior?
Using the "maximizable" property !

Please tell us about your environment:

Linux Mint, VS Code, NPM, NodeJS

• Angular version: 5.X
  Angular 6.0.5

• PrimeNG version: 5.X
  PrimeNG 6.0.0-rc.1

• Browser: [all | Chrome XX | Firefox XX | IE XX | Safari XX | Mobile Chrome XX | Android X.X Web Browser | iOS XX Safari | iOS XX UIWebView | iOS XX WKWebView ]
  Chrome, Chromium, Opera, Firefox

• Language: [all | TypeScript X.X | ES6/7 | ES5]
  Typescript 2.7.2