* fix(xslt): resolve document() references against the correct base URI
The document() function resolved every relative URI reference against the
single global base, so a reference relative to a document that document()
itself had loaded from a subdirectory could not be found. XSLT 1.0 12.1
defines the base per reference: the two-argument form against the second
argument's first node, the node-set form against each reference node's own
document.
Each loaded document now records the URI it came from as its base, and a
relative reference resolves against that base before the loader applies its
own source-document base. The common one-argument string form is unchanged
(its base is empty, deferring to the loader as before).
Closes Apache Xalan conformance cases reluri09, reluri10, reluri11.
* fix(xslt): record base URI for document() fragment selections
A fragment selection (document('x#frag')) is returned as a detached subtree
whose root identity differs from the cached whole-document tree, so its base
URI was not recorded. Using such a node as the base for a relative document()
reference then resolved against the empty base instead of the fragment's
document. Record the base on each fragment subtree's own root through a shared
helper, so baseURI(of:) finds it whichever node the reference is taken from.
Mihaela Mihaljevic
b6af499558