Don't force layout for mouse event hit tests

LayoutTests/touchadjustment/block-testing.html

Index: LayoutTests/touchadjustment/block-testing.html
diff --git a/LayoutTests/touchadjustment/block-testing.html b/LayoutTests/touchadjustment/block-testing.html
index 9d7b4ff877ac0fe31ae47cc2d9dca07673ebb94a..bfa738eea9597a94a3a47fe6290f8f4389183a84 100644
--- a/LayoutTests/touchadjustment/block-testing.html
+++ b/LayoutTests/touchadjustment/block-testing.html
@@ -37,6 +37,8 @@
         {
             if (window.testRunner && window.internals && internals.touchNodeAdjustedToBestClickableNode) {
                 description('Test touch-adjustment on a block where we also touch the inner text and outside link.');
+                // Mouse events only work after an initial layout
+                document.body.offsetLeft;
                 testDirectTouches();
                 document.getElementById('sandbox').style.display = 'none';
             }
@@ -45,4 +47,4 @@
     </script>
     <script src="../fast/js/resources/js-test-post.js"></script>
 </body>
-</html>
+</html>