Enable sticky positioning for table elements.

LayoutTests/fast/css/sticky/sticky-table-thead-top-expected.html

Index: LayoutTests/fast/css/sticky/sticky-table-thead-top-expected.html
diff --git a/LayoutTests/fast/css/sticky/sticky-top-expected.html b/LayoutTests/fast/css/sticky/sticky-table-thead-top-expected.html
similarity index 83%
copy from LayoutTests/fast/css/sticky/sticky-top-expected.html
copy to LayoutTests/fast/css/sticky/sticky-table-thead-top-expected.html
index eca9bcf536dd40c957c8e1d3c7e86d1d2a43b8ea..ccb6f9173e9d3b2839641472b5bb4a93b6575488 100644
--- a/LayoutTests/fast/css/sticky/sticky-top-expected.html
+++ b/LayoutTests/fast/css/sticky/sticky-table-thead-top-expected.html
@@ -5,21 +5,23 @@
 <style>
     body {
         margin: 0;
+        height: 2000px;
+        overflow: hidden; /* hide scrollbars */
     }
-    
+
     .group {
         display: inline-block;
         position: relative;
         width: 250px;
         height: 500px;
     }
-    
+
     .container {
         width: 200px;
         height: 400px;
         outline: 2px solid black;
     }
-    
+
     .box {
         width: 200px;
         height: 200px;
@@ -29,7 +31,7 @@
         position: absolute;
         background-color: green;
     }
-    
+
     .indicator {
         position: absolute;
         top: 0;
@@ -59,5 +61,9 @@
             <div class="sticky box" style="top: 0;"></div>
         </div>
     </div>
+    <div style="position: absolute; top: 520px;">
+    This test checks that sticky positioned table theads are contained by their table.
+    There should be no red.
+    </div>
 </body>
 </html>