| Index: LayoutTests/fast/dom/HTMLDialogElement/top-layer-containing-block-scrolled-viewport.html | 
| diff --git a/LayoutTests/fast/dom/HTMLDialogElement/top-layer-containing-block-scrolled-viewport.html b/LayoutTests/fast/dom/HTMLDialogElement/top-layer-containing-block-scrolled-viewport.html | 
| new file mode 100644 | 
| index 0000000000000000000000000000000000000000..69200afccb65440c306e0a931f60730a8901ad76 | 
| --- /dev/null | 
| +++ b/LayoutTests/fast/dom/HTMLDialogElement/top-layer-containing-block-scrolled-viewport.html | 
| @@ -0,0 +1,28 @@ | 
| +<!DOCTYPE html> | 
| +<html> | 
| +<head> | 
| +<script> | 
| +if (window.internals) | 
| +    internals.settings.setDialogElementEnabled(true); | 
| +</script> | 
| +</head> | 
| +<body style="height: 10000px; width: 10000px"> | 
| +<p style="position: fixed"> | 
| +This tests that a top layer element's containing block is the initial containing | 
| +block. The dialog is positioned at (1200, 1200) and the window is scrolled to | 
| +(1000, 1000) so the dialog should be positioned at (200, 200) relative to the | 
| +viewport. | 
| +</p> | 
| +<div style="position: absolute; top: 5000px; left: 5000px; width: 20px;"> | 
| +    <dialog id="dialog" style="top: 1200px; left: 1200px; right: auto; height: 250px; width: 50%; background-color: yellow"> | 
| +        This dialog should be onscreen with a width of 50% of the viewport. It is the child of an narrow element | 
| +        positioned off screen, but its containing block is the initial containing block, so its | 
| +        position and percent lengths are relative to that. | 
| +    </dialog> | 
| +</div> | 
| +<script> | 
| +window.scroll(1000, 1000); | 
| +document.getElementById('dialog').showModal(); | 
| +</script> | 
| +</body> | 
| +</html> | 
|  |