This expands the InspectorWidget::Selection to include an optional
PseudoElement, which is then passed over IPC to request style
information for it.
As noted, this has some pretty big limitations because pseudo-elements
don't have DOM nodes:
- Declared style has to be recalculated when it's requested.
- We don't display the computed style.
- We don't display custom properties.
This Adds an element size preview widget to the inspector widget
in a new tab. This functions similar to chrome and firefox and
shows the margin, border, padding, and content size of the selected
element in the inspector.
The colors for the size preview widget are taken from the chrome
browser.
