When detecting an element's opening tag, the spec asks us to skip ahead
to the first whitespace or end chevron character before trying to read
attributes. Instead, we were always skipping 2 positions ahead and then
ignoring all whitespace characters and slashes, which was clearly wrong.
Theoretically this could have caused some weird behaviors if part of the
opening tag matched an expected attribute name, but it's very unlikely
to see that in the wild.
This did not cause any immediate issues except generating instances of
`Attr` with useless values which caused some unnecessary work during
encoding detection.
Previously, the charset of name "UTF-16BE/LE" would be checked against
when following standards to convert the charset to UTF-8, but in
reality, the charsets "UTF-16BE" and "UTF-16LE" should be checked
separately.
Co-authored-by: Jelle Raaijmakers <jelle@ladybird.org>
Resulting in a massive rename across almost everywhere! Alongside the
namespace change, we now have the following names:
* JS::NonnullGCPtr -> GC::Ref
* JS::GCPtr -> GC::Ptr
* JS::HeapFunction -> GC::Function
* JS::CellImpl -> GC::Cell
* JS::Handle -> GC::Root
