У вашего броузера проблема в совместимости с HTML5
How To Enable Developer Option On Oppo F1s.
Step To Enable Developer Option OPPO F1s & Plus:
1. Go To Setting
2. Tap On About Phone
3. Tap 7 Time on Version
4. Go To Setting
5. Tap On Additional Settings
6. Tap On Developer Options
7. Enter verification code
To enable debugging mode tap on USB debugging.