Normally, assigning to e.g document.body.onload will forward to
window.onload. However, in a detached DOM tree, there is no associated
window, so we have nowhere to forward to, making this a no-op.
The bulk of this change is making Document::window() return a nullable
pointer, as documents created by DOMParser or DOMImplementation do not
have an associated window object, and so must be able to return null
from here.
On platinenmacher.tech there is a document without a window. During
size attribute parsing the window pointer is dereferenced which
causes a crash. This checks for the window to be actually there
before dereferencing.
When parsing these, <number> is allowed anywhere that would usually
allow a <length>, <length-percentage>, or <angle>. The spec is not
clear on exactly how this should work
(see https://github.com/w3c/svgwg/issues/792 ) so I'm using some
artistic license until things are clearer:
- If we expected a <length>, treat the <number> as pixels.
- If we expected an <angle>, treat the <number> as degrees.
- Only allow direct <number> tokens, not calc() or other functions.
From what I can tell this is what the spec *intended* but I may be very
wrong. In any case, telling the ParsingContext whether we're parsing
one of these attributes is a cleaner approach and more correct than
temporarily enabling quirks mode, which we did previously.
