Update CustomElementConstructor type and exception

[jdm]

The IDL for CustomElementConstructor was changed in whatwg/html#4525. We should update that as well as the exception used by this code.

To test these changes, we will need the tests in web-platform-tests/wpt#16328.

[gatoWololo]

Cool. I think I understand this. I can do it.

[gatoWololo]

We should update that as well as the exception used by this code.

I have found 2 places where we need to change from Error::InvalidState to Error::Type. The one you pointed out above. and

servo/components/script/dom/bindings/htmlconstructor.rs

Line 185 in 1e158bb

Some(ConstructionStackEntry::AlreadyConstructedMarker) => Err(Error::InvalidState),

To test these changes, we will need the tests in web-platform-tests/wpt#16328.

The tests are already in Servo here and here, and they are the latest version using TypeError.

After changing to Error::Type and running:
./mach test ./tests/wpt/web-platform-tests/custom-elements/upgrading/upgrading-parser-created-element.html
./mach test ./tests/wpt/web-platform-tests/custom-elements/upgrading/Node-cloneNode.html

I can confirm all the [expected FAIL] tests related to TypeError, now pass :)

My only question: I'm not sure what String to pass to Error::Type(String)?
Currently, I have something like:

        if !same {
            return Err(Error::Type("Returned element is not SameValue as the upgraded element".to_string()));

Is this what's expected? Or is there somewhere specific to get the correct string from?

[jdm]

Strings are implementation-defined, so that one seems fine.