Bug 45205: Test that <xml-stylesheet> processing instructions only have stylesheets when in document.

PASS successfullyParsed is true

TEST COMPLETE

PASS sheet.ownerNode is pi
PASS pi.sheet === sheet is true
Removing <pi>...
PASS pi.sheet is null
PASS sheet.ownerNode is null
PASS sheet.cssRules[0].cssText[0] is "*"
Re-adding <pi>...
PASS sheet.ownerNode is null
PASS pi.sheet === sheet is false
PASS pi.sheet.ownerNode is pi