gambas3-gb-qt5-webkit software package provides Gambas WebKit component, you can install in your Debian 9 (Stretch) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gambas3-gb-qt5-webkit
gambas3-gb-qt5-webkit is installed in your system.
Make ensure the gambas3-gb-qt5-webkit package were installed using the commands given below,
$ sudo dpkg-query -l | grep gambas3-gb-qt5-webkit *
You will get with gambas3-gb-qt5-webkit package name, version, architecture and description in a table
| Distro | Debian 9 stretch |
| Section | KDE |
| Package | gambas3-gb-qt5-webkit |
| Version | 3.9.1-1 |
| Description | Gambas WebKit component |
| Sub Section | KDE |