Make set_mark searching tests less flaky.

Replace all the html numbers with a few widely spaced divs to guarantee the
search will move the viewport on almost and reasonable screen size.

tests/integration/data/marks.html

@@ -8,109 +8,9 @@
         <h1 id="top">Top</h1>
         <a href="#top">Top</a>
         <a href="#bottom">Bottom</a>
-        <pre>
-0
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-This is a very long line so this page can be scrolled horizontally. Did you think this line would end here already? Nah, it does not. But now it will. Or will it? I think it's not long enough yet.
-        </pre>
+        <div style="height: 3000px; width: 3000px;">Holy Grail</div>
+        <div style="height: 3000px; width: 3000px;">Waldo</div>
+        <div style="height: 3000px; width: 3000px;">Holy Grail</div>
         <h1 id="bottom">Bottom</h1>
     </body>
 </html>

tests/integration/features/marks.feature

@@ -71,16 +71,13 @@ Feature: Setting positional marks
         Then the page should be scrolled to 0 0
 
     Scenario: Jumping back after searching
-        When I run :hint links normal
-        And I run :search 48
+        When I run :scroll-px 20 15
+        And I run :search Waldo
         And I run :jump-mark "'"
-        Then the page should be scrolled to 0 0
+        Then the page should be scrolled to 20 15
 
     Scenario: Jumping back after search-next
-        When I run :hint links normal
-        And I run :search 9
-        And I run :search-next
-        And I run :search-next
+        When I run :search Grail
         And I run :search-next
         And I run :jump-mark "'"
         Then the page should be scrolled to 0 0