Instead of creating a display list for the entire page, only create one
for an area that expands around the viewport. On my machine this makes
incremental layout of http://timecube.com 50% faster.
Instead of looking at the display tree, have ContentBox(es)Query consult
the flow tree. This allow optimizing away parts of the display tree
later. To do this we need to be more careful about how we send reflow
requests, only querying the flow tree when possible.
Fixes#3790.
This patch puts in the initial framework for incremental reflow. Nodes' styles
are no longer recalculated unless the node has changed.
I've been hacking on the general problem of incremental reflow for the past
couple weeks, and I've yet to get a full implementation that actually passes all
the reftests + wikipedia + cnn. Therefore, I'm going to try to land the different
parts of it one by one.
This patch only does incremental style recalc, without incremental flow
construction, inline-size bubbling, reflow, or display lists. Those will be coming
in that order as I finish them.
At least with this strategy, I can land a working version of incremental reflow,
even if not yet complete.
r? @pcwalton
