--- a/layout/forms/test/test_bug1301290.html
+++ b/layout/forms/test/test_bug1301290.html
@@ -30,17 +30,17 @@
         <div class="blue"></div>
         <textarea class="green" id="textarea"></textarea>
         <script type="application/javascript">
             SimpleTest.waitForExplicitFinish();
             addLoadEvent(() => SimpleTest.executeSoon(function() {
                 var textarea = $("textarea");
                 var rect = textarea.getBoundingClientRect();
 
-                synthesizeMouse(textarea, rect.width - 10, rect.height - 10, { type: "mousedown" });
+                synthesizeMouse(textarea, rect.width - 9,  rect.height - 9,  { type: "mousedown" });
                 synthesizeMouse(textarea, rect.width + 40, rect.height + 40, { type: "mousemove" });
                 synthesizeMouse(textarea, rect.width + 40, rect.height + 40, { type: "mouseup" });
 
                 var newrect = textarea.getBoundingClientRect();
                 ok(newrect.width > rect.width, "width did not increase");
                 ok(newrect.height > rect.height, "height did not increase");
                 SimpleTest.finish();
             }));