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.
Each HtmlView now has a main_frame(), which represents the main frame
of the web page. Frame inherits from TreeNode<Frame>, which will allow
us to someday implement a Frame tree (to support the <frame> element.)
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.
You can now query Document::title() to get a String containing whatever
is inside the document's <title> tag.
In support of this, this patch adds the <html>, <head> and <title>
elements.
This is a simple command that can be used to display HTML from a given
file, or from the standard input, in an HtmlView. It replaces the `tho`
(test HTML output) command.
