To prepare for fully qualified tag names, let's call this local_name.
Note that we still keep an Element::tag_name() around since that's what
the JS bindings end up calling into for the Element.tagName property.
To make this possible, I also had to give each LayoutNode a Document&
so it can resolve document-specific colors correctly. There's probably
ways to avoid having this extra member by resolving colors later, but
this works for now.
We will no longer create bitmap buffers for canvases that exceed a
total area of (16384 * 16384) pixels. This matches what some other
browser do.
Thanks to @itamar8910 for finding this! :^)
This patch adds HTMLCanvasElement along with a LayoutCanvas object.
The DOM and layout parts are very similar to <img> elements.
The <canvas> element holds a Gfx::Bitmap which is sized according to
the "width" and "height" attributes on the element.
Calling .getContext("2d") on a <canvas> element gives you a context
object that draws into the underlying Gfx::Bitmap of the <canvas>.
The context weakly points to the <canvas> which allows it to outlive
the canvas element if needed.
This is really quite cool. :^)
