When we open a background tab, it gets a hardcoded size (800x600 or so) because
it doesn't get resized by the layout yet.
By resizing it to the size it'll actually have later, we make sure scrolling to
an anchor in an background tab works, and JS also gets the correct size for
background tabs.
Fixes#1190Fixes#2495
See #1417
We now use click() or focus() in JS if possible, or manually follow links in a
href attribute.
While this probably introduces some new corner cases, it fixes a handful of
older ones:
- window.open() in JS can now be handled correctly as we don't need hacks in
createWindow anymore.
- Focusing input fields with images now works - fixes#1613, #1879
- Hinting now works better on QtWebEngine with Qt 5.8 - fixes#2273
Also see #70.
