Selector: Fix test iframe submission for firefox

Ref jquery/sizzle@20fbadb0870bd30e0e66c68891f121c0450374c4
Selector: Use jQuery reference not Sizzle
Tests: Apply namespace for QUnit globals

Ref jquery/qunit#577
Tests: Apply namespace for QUnit assertions
Tests: Remove unused QUnit globals from .jshintrc

plus detected fixings