Note our Attribute class is what the spec refers to as just "Attr". The
main differences between the existing implementation and the spec are
just that the spec defines more fields.
Attributes can contain namespace URIs and prefixes. However, note that
these are not parsed in HTML documents unless the document content-type
is XML. So for now, these are initialized to null. Web pages are able to
set the namespace via JavaScript (setAttributeNS), so these fields may
be filled in when the corresponding APIs are implemented.
The main change to be aware of is that an attribute is a node. This has
implications on how attributes are stored in the Element class. Nodes
are non-copyable and non-movable because these constructors are deleted
by the EventTarget base class. This means attributes cannot be stored in
a Vector or HashMap as these containers assume copyability / movability.
So for now, the Vector holding attributes is changed to hold RefPtrs to
attributes instead. This might change when attribute storage is
implemented according to the spec (by way of NamedNodeMap).
This patch implements the HTML specification's "encoding sniffing
algorithm", which is used when no encoding can be obtained from the
Content-Type header (either because it doesn't contain a charset=...)
value or the file has not been opened via HTTP (as with local files).
It also modifies the creator of the HTMLDocumentParser to use the new
HTMLDocumentParser::create_with_uncertain_encoding static method, which
runs the encoding sniffing algorithm before instantiating the parser.
This now allows us to load local HTML pages (or remote pages without a
charset specified in the 'Content-Type' header) with a non-UTF-8
encoding such as 'windows-1252'. This would previously crash the
browser. :^)
