Previously, HTMLToken would expose the Vector<Attribute> directly to
its users. In preparation for a future change, all users now use
implementation-agnostic APIs which do not expose the Vector directly.
This fixes parsing the following regular expression: /</g;
It also adds a simple script element to the HTMLTokenizer regression
test, which also contains that specific regex.
The test suite includes a few basic tests and a very crude regression
test, which just concatenates the to_string() of all tokens and checks
the String's hash to be equal. This relies on the format of
HTMLToken::to_string() to stay the same, which is not ideal.
Previously, AK::Function would accept _any_ callable type, and try to
call it when called, first with the given set of arguments, then with
zero arguments, and if all of those failed, it would simply not call the
function and **return a value-constructed Out type**.
This lead to many, many, many hard to debug situations when someone
forgot a `const` in their lambda argument types, and many cases of
people taking zero arguments in their lambdas to ignore them.
This commit reworks the Function interface to not include any such
surprising behaviour, if your function instance is not callable with
the declared argument set of the Function, it can simply not be
assigned to that Function instance, end of story.
