Bug 862485 - Split test_pointer-events.xhtml in two to avoid timeouts. r=longsonr

--HG--
rename : content/svg/content/test/test_pointer-events.xhtml => content/svg/content/test/test_pointer-events-1a.xhtml
rename : content/svg/content/test/test_pointer-events.xhtml => content/svg/content/test/test_pointer-events-1b.xhtml