Merge pull request #5473 from opf/test/contain-strict

Check contain:strict for extremely long timelines

app/assets/stylesheets/layout/_work_package_table.sass

@@ -113,7 +113,7 @@
   // Hint browser that this will inner-scroll
   will-change: transform
   // Hinter browser that the content of the flex is contained
-  contain: content
+  contain: strict
 
   &.-timeline-visible
     // Show the horizontal scrollbar if necessary
@@ -131,7 +131,7 @@
   // Hint browser that this will inner-scroll
   will-change: transform
   // Hinter browser that the content of the flex is contained
-  contain: content
+  contain: strict
 
 .work-packages--edit-actions
   .work-packages--left-panel &