So we get
it("tests.xml, function () {
it("test1", function () {
}
it("test2", function () {
}
}

Having a test factory that creates the tests for the elements in the xml
is much easier to maintain. I dont quite get how 'each individual “it”
test is specified from the source XML'.

With jasmine you nest the describe blocks to group sets tests[1].

So, integrating some XML-based tests could be done like:

describe("Operation transform matrix tests", function () {
    it("constructs successfully", function() { ... });
    it("cleans up all things on teardown", function() { ... });

    describe("XML-based transform tests", function() {
        var xmlFile = runtime.readFileSync(...),
            tests = parseTests(xmlFile);

        tests.forEach(function(test) {
            it(test.name, test.func);
        });
    });
});