1 This tests that a modal dialog's containing block is the initial containing block.
2 The dialog should be onscreen with a width of 50% of the viewport. It is the child of a narrow element positioned off screen, but its containing block is the initial containing block, so its position and percent lengths are relative to that.
3 PASS dialog.offsetParent is null
4 PASS dialog.offsetTop is 1200
5 PASS dialog.offsetLeft is 1200
6 PASS dialog.clientWidth is expectedWidth
7 PASS successfullyParsed is true