Add onmessageerror to WindowEventHandler
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Fix PromiseRejectionEvent constructor when promise argument is None
Due to lack of `required` of the `promise` argument in webidl, we need to handle this so that it can be correct behavior. And then the constructor test will be passed!
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Use the newly stored line as the starting line number when
evaluating JS. This ensures that inline scripts will report
errors with meaningful line numbers.
If the last child of a node is a Text child and we are inserting text in that node,
we need to append it to that Text child. Doing that means that
HTMLStyleElement::children_changed gets called less frequently, but that's not a
problem during parsing thanks to the pop hook.
Adding:
* global event handlers,
* window event handlers,
* document and element handlers,
* and support for BeforeUnloadEvent.
Signed-off-by: Piotr Stankiewicz <bionicrift@gmail.com>
