LayoutReplaced objects can now participate in inline layout.
It's very hackish, but basically LayoutReplaced will just add itself to
the last line in the containing block.
This patch gets rid of the idea that only LayoutInline subclasses can
be split into lines, by moving the split_into_lines() virtual up to
LayoutNode and overriding it in LayoutReplaced.
There was nothing left in ComputedStyle except the box model metrics,
so this patch gives it a more representative name.
Note that style information is fetched directly from StyleProperties,
which is basically the CSS property name/value pairs that apply to
an element.
This patch makes StyleProperties heap-allocated and ref-counted so that
a LayoutNode can be without one. The ref-counting also allows anonymous
blocks to share style with their parent block.
LayoutText never needs a StyleProperties, since text always inherits
style from its parent element. This is handled by style_properties().
Inline layout is now done by LayoutBlock. Blocks with inline children
will split them into line boxes during layout.
A LayoutBlock can have zero or more LineBox objects. Each LineBox
represents one visual line.
A LineBox can have any number of LineBoxFragment children. A fragment
is an offset+length into a specific LayoutNode.
To paint a LayoutBlock with inline children, we walk its line boxes,
and walk their fragments, painting each fragment at a time by calling
LineBoxFragment::render(), which in turn calls the LayoutNode via
LayoutText::render_fragment(). Hit testing works similarly.
This is very incomplete and has many bugs, but should make it easier
for us to move forward with this code.
LayoutBlock::inline_wrapper() is supposed to return an inline wrapper,
a special anonymous block element intended to wrap inline children of
a block element that also has block children. Add a check for whether
the existing block child element is anonymous (refers to a DOM node),
and if it's not create a new anonymous wrapper.
