Self Closing Foreign Content

Test for https://bugs.webkit.org/show_bug.cgi?id=55955. Verify that WebKit does not ASSERT when a self-closing svg or mathml root element is followed by non-foreign HTML content. In the fragment case, this ASSERT indicated that the parser's insertion mode was incorrectly in InForeignContentMode even though the svg or mathml root element was self-closing and not placed on the open elements stack.