App Version: M63.0.3239.33 beta
iOS Version: 10.3.3, 11.2
Device: iPhone6s, iPhone7 plus
URL: http://www.mediacollege.com/internet/javascript/page/scroll.html 

Steps to reproduce:
  1. Launch Google Chrome
  2. Navigate to above page
  3. Scroll down the page slightly to enter fullscreen mode
  4. Tap "Scroll Page" button and wait for the page to completley autoscroll to the end of the page
  5. Try to scroll up

Observed results: Scroll up is not possible anyway because of the autoscroll, but browser toolbar is not displayed. 

Expected results: Browser toolbar should be displayed when trying to scroll up

Number of times you were able to reproduce: 5/5
Bug reproducible after clean install: Yes
Bug reproducible after clearing cache and cookies: Yes
Bug reproducible on Chrome Mobile on Android: Not tested
Bug reproducible on Safari/Firefox: Firefox: NO, Safari: NO (Works fine in both browsers)
Bug reproducible on current stable build (App Version, iOS Version): M62 Yes
Bug reproducible on the current beta channel build (App Version, iOS Version): M63 Yes

Link to video/image: https://drive.google.com/file/d/1d5eARdate0LDU3Ra39klBDtFBdmvPJVG/view