In order to tailor certain security checks to the caller that is
attempting to load a particular piece of content, we need to be able to
attach an appropriate triggering principal to the corresponding requests.
Since most HTML content is loaded based on attribute values, this means
capturing the subject principal of the caller who sets those attributes,
which in turn means we need to make it available to `AfterSetAttr` hooks
on all relevant element types.
QIing to CC interfaces is a hot path for a few widely-used classes.
Presumably there are many of these objects being created and destroyed.
By making these classes check first for the CC interfaces directly, rather
than going up the inheritance chain, the resulting overhead is reduced.
Since these are just interpreted comments, there's 0 impact on actual code.
This removes all lines that match /* vim: set(.*)tw=80: */ with S&R -- there are
a few others scattered around which will be removed manually in a second part.
* Moves side effects of nsGenericHTMLElement and Element's SetAttr, UnsetAttr, and ParseAttribute functions to the corresponding BeforeSetAttr and AfterSetAttr functions
* Moves side effects of HTMLAnchorElement's SetAttr, UnsetAttr, and ParseAttribute functions to the corresponding BeforeSetAttr and AfterSetAttr functions
* Moves side effects of HTMLImageElement's SetAttr function to the corresponding BeforeSetAttr and AfterSetAttr functions
* Moves side effects of SetAttr, UnsetAttr, and ParseAttribute functions to BeforeSetAttr and AfterSetAttr
Tag #1375
