xpath: Throw a NAMESPACE_ERR DOMException when namespace resolver callback returns invalid value or throws

[simonwuelker]

I always thought that exceptions thrown in namespace resolver callbacks should be propagated to the call site of document.evaluate.
That is not the case - the exception is silently swallowed and you get a namespace error, the same as if the callback had returned any other invalid value.

Testing: New web platform tests start to pass
Fixes #39931
Part of #34527

[simonwuelker]

Needs some more investigation because some subtests in resolver-callback-interface.html do expect a type error to be thrown.

[simonwuelker]

Chrome also fails those two remaining tests: https://wpt.fyi/results/domxpath/resolver-callback-interface.html?label=master&label=experimental&product=servo&product=firefox&product=chrome&aligned&q=domxpath

Firefox somehow throws both a type error and a namespace DOMException in the same document.evaluate call, which matches the test expectations. I wasn't able to replicate that, but if chrome isn't doing it then there's likely no point...