[Web Browser] Use more appropriate panel icon and increase default size
If you add an applet not to the desktop, but to the panel, then the old icon is out of the general design of the panel, and the size of the browser window does not allow reading the contents. Changes fix this.
Reviewers: ematirov, Plasma, broulik
Reviewed By: Plasma, broulik
Subscribers: ngraham, plasma-devel
Differential Revision: https://phabricator.kde.org/D19417