Youtube causes a panic

[Manishearth]

Not that youtube should be working anyway, but we shouldn't be panicking there

ERROR:constellation::constellation: Panic: called `Result::unwrap()` on an `Err` value: IdnaError
ERROR:constellation::constellation: Backtrace:
frame #0  - 0x0000000108a5309e - backtrace::backtrace::trace::hccde8df28b4db2a2
frame #1  - 0x0000000108a53021 - backtrace::capture::Backtrace::new::h42f95930bb8c5ee8
frame #2  - 0x0000000107d17236 - _<F as alloc..boxed..FnBox<A>>::call_box::h24a37968568e1cc2
frame #3  - 0x00000001089c2c47 - util::panicking::initiate_panic_hook::_$u7b$$u7b$closure$u7d$$u7d$::_$u7b$$u7b$closure$u7d$$u7d$::hf0802d30a2c12199
frame #4  - 0x0000000108c38b54 - std::panicking::rust_panic_with_hook::h983af77c1a2e581b
frame #5  - 0x0000000108c51a96 - std::panicking::begin_panic::he426e15a3766089a
frame #6  - 0x0000000108c3a198 - std::panicking::begin_panic_fmt::hdddb415186c241e7
frame #7  - 0x0000000108c516ef - rust_begin_unwind
frame #8  - 0x0000000108c78570 - core::panicking::panic_fmt::hf4e16cb7f0d41a25
frame #9  - 0x0000000107b066a9 - core::result::unwrap_failed::hf81255c6633560f3
frame #10 - 0x0000000107babbdc - _<script..dom..htmlimageelement..HTMLImageElement as script..dom..virtualmethods..VirtualMethods>::attribute_mutated::hcd638d26442e3ffe
frame #11 - 0x0000000107b37938 - script::dom::element::Element::push_attribute::h1471b6b0f0b21238
frame #12 - 0x0000000107b37254 - script::dom::element::Element::push_new_attribute::h8194d0ae4e1a8a94
frame #13 - 0x0000000107afbff2 - script::dom::element::Element::set_attribute::h2dd6822acf689f0a
frame #14 - 0x0000000107b39b16 - script::dom::element::Element::set_string_attribute::h421bed07a514004a
frame #15 - 0x00000001077cc866 - _<script..dom..htmlimageelement..HTMLImageElement as script..dom..bindings..codegen..Bindings..HTMLImageElementBinding..HTMLImageElementMethods>::SetSrc::h6549ab1a65ae07b2
frame #16 - 0x00000001077cc7cf - std::panicking::try::call::he57edb213a93aafb
frame #17 - 0x0000000108c5477b - __rust_try
frame #18 - 0x0000000108c54715 - __rust_maybe_catch_panic
frame #19 - 0x00000001077cc635 - script::dom::bindings::codegen::Bindings::HTMLImageElementBinding::set_src::h61e2db98f3ada3bf
frame #20 - 0x000000010832e1da - CallJitSetterOp
frame #21 - 0x00000001075750ed - script::dom::bindings::utils::call_setter::h4469a2055caddbb9
frame #22 - 0x0000000107574faa - script::dom::bindings::utils::generic_call::h0e13687f0f086f31

[Manishearth]

Looks like the panic is on parsing the punycode URL https://r2---sn-huoa-cvhl.googlevideo.com/crossdomain.xml with a youtube base URL.

[Manishearth]

servo/rust-url#207 is the parse error.

We shouldn't be crashing in the image load anyway.