Debug printing widgets was quite verbose. While developing a widget, you
often want to see a full debug printout, but this feature assumes that
debug printing a WidgetInstance should show a summary of the widget, not
a full debug printout containing cached glyph information of every
label.
By default, summarize just calls Debug, but this extra layer allows
widgets to provide a more condensed summary and exclude details like
caches.
Originally, adding dbg!() around the theme example's UI yielded a
whopping 20,324 lines of text. The summary code only prints 3,858
lines.
Scroll was previously taking the graphics region as its control size as
opposed to the constraints. This was due to this code originally living
in redraw. This fixes scroll areas being able to scroll their contents
fully when sharing window space with other widgts.
measure() now is layout(). LayoutContext can either persist layout
information or be used temporarily for measurement. While this caching
is constantly thrown out currently, this is a step towards being able to
only re-layout widgets if they've been invalidated.
