298959 - Find a better way for RS tags to not override fonts and sizes

Status: RESOLVED FIXED

(Core :: DOM: HTML Parser, defect)

Description

[Blake Kaplan (:mrbkap) (inactive)]

Currently, when faced with |<font size=10><h1>foo|, we perform residual style
handling as usual. The problem with this is that people expect the <h1> to take
precedence over the <font> and when the RS handling kicks in, we get a content
model of <h1><font size=10>foo</font></h1>, so the <font> takes precedence
causing pain and unhappiness.

In order to fix this, when we emit a residual style tag when a heading tag is on
the stack, we put a an attribute on the residual style tag (_moz-rs-heading) and
use a rule in quirk.css to inherit the font size.

While going through parser bugs, I noticed a lot of bugs reported on a similar
problem: |<font face=...><pre>foo| where the <font face> takes precedence over
the <pre>. I talked to jst about doing something similar to what we do for
headings and while he was okay for the general idea, he didn't like the idea of
having a real attribute in the DOM as a result of RS handling.

There are a couple of options we can use in place of this (such as using content
state and content properties). I'm opening this as a bug to:
a) Not use the attribute in the DOM for this purpose
b) Fix the <font><pre> case.

Comment 1

[Boris Zbarsky [:bzbarsky]]

Note that matching on attributes is slow; if we can use a class that would be
better...