This ensures that the layout viewport responds to each type of zoom correctly,
and lays the ground for CSS Media Queries and CSS Device Adaption.
Until we have proper touch support, mobile-style "pinch" zoom can be simulated
by holding Ctrl while scrolling with a mousewheel or trackpad gesture.
This fixes an issue where the CSS viewport was too large on high-DPI displays
because it was set to the window size in device pixels, instead of px. This
patch ensures that the window size is converted from device pixels to px
before being passed to script/layout code.
The Window trait now exposes the window size in both device pixels and
density-independent screen coordinates, with clearer method names.
April 10, 2014. The main changes are to privacy, to work around the
issues with incorrect bounds on the libstd `Arc<Mutex<T>>`, and the
various API changes strewn throughout the libraries.
Pointers to DOM nodes from layout could go stale if incremental reflow
does not correctly destroy dead nodes. Therefore, we ask the JavaScript
garbage collector to verify that each DOM node is indeed a valid pointer
before calling event handlers on it, and fail otherwise.
This replaces flow construction with a strict bottom-up tree traversal,
allowing for parallelism. Each step of the traversal creates a flow or
a `ConstructionItem`, similar to how Gecko works. {ib} splits are
handled by not creating `InlineFlow`s until the containing block is
reached.
This should be able to be incrementalized by storing the `Flow` from
layout to layout, and performing fixups during flow construction
and/or wiping containing blocks in a previous pass.
