▶ TIMEOUT [expected OK] /webgl/conformance-1.0.3/conformance/rendering/gl-scissor-test.html
  │ 
  │ DESCRIPTION: Check if glScissor setting works.
  │ test antialias: false
  │ PASS context exists
  │ 
  │ test with clear
  │ checking rect: effective width or height is zero
  │ PASS should be black
  │ ERROR:js::rust: Error at http://web-platform.test:8000/webgl/conformance-1.0.3/conformance/resources/webgl-test-utils.js:1034:4: gl.readPixels is not a function
  │ 
  │ FAIL successfullyParsed should be true (of type boolean). Was undefined (of type undefined).
  │ TEST COMPLETE
  │ thread 'PaintWorker' panicked at 'assertion failed: (data.len() as i32) >= stride * size.height', /Users/servo/.cargo/git/checkouts/rust-azure-97bcec2370a94878/master/src/azure_hl.rs:710
  │ stack backtrace:
  │    1:        0x1022d42d8 - std::sys::backtrace::tracing::imp::write::h714760a4c8c0cdd8
  │    2:        0x1022da5b5 - std::panicking::default_hook::_$u7b$$u7b$closure$u7d$$u7d$::hff309ab1d83ffd90
  └    3:        0x1022da1ce - std::panicking::default_hook::h08ad3bb09872855b