fix getComputedStyle positioned element values

third_party/WebKit/LayoutTests/fast/dom/HTMLDialogElement/abspos-dialog-layout.html

Index: third_party/WebKit/LayoutTests/fast/dom/HTMLDialogElement/abspos-dialog-layout.html
diff --git a/third_party/WebKit/LayoutTests/fast/dom/HTMLDialogElement/abspos-dialog-layout.html b/third_party/WebKit/LayoutTests/fast/dom/HTMLDialogElement/abspos-dialog-layout.html
index 957197bb3bf68f84b0451dc342f347d04bb239f3..477cfa2be90cadccfaab292cf5ee92c8425e0d14 100644
--- a/third_party/WebKit/LayoutTests/fast/dom/HTMLDialogElement/abspos-dialog-layout.html
+++ b/third_party/WebKit/LayoutTests/fast/dom/HTMLDialogElement/abspos-dialog-layout.html
@@ -35,11 +35,11 @@ reset();
 }());
 
 (function() {
-    debug('<br>The computed top and bottom of a centered dialog should still have position auto.');
+    debug('<br>The dialog is a positioned element, so the top and bottom should not have style auto.');
 
     dialog.showModal();
-    shouldBeEqualToString('window.getComputedStyle(dialog).top', 'auto');
-    shouldBeEqualToString('window.getComputedStyle(dialog).bottom', 'auto');
+    shouldBeEqualToString('window.getComputedStyle(dialog).top', '790px');

[mstensho (USE GERRIT), 2016/04/04 09:13:26]

Yes, I think this is reasonable and correct behavior. The dialog is centered. If
the viewport (and initial containing block) height is 600px, and line height is
20px, we end up with a dialog whose top is 290px below the top of the initial
containing block and whose bottom is 290px above the bottom of the ICB. However,
we are scrolled by 0,500, so when the dialog is opened, its position is adjusted
accordingly. The ICB is always at scroll position 0,0, no matter what the actual
scroll position is.

Since Blink is the only engine that supports DIALOG, we have nobody to compare
against, though.

[Mr. Kevin, 2016/04/04 17:35:22]

Acknowledged.

+    shouldBeEqualToString('window.getComputedStyle(dialog).bottom', '-210px');
     reset();
 }());