Don't force layout for mouse event hit tests

LayoutTests/svg/custom/resources/focus-event-handling.js

 var focusinSeen = "";
 var focusoutSeen = "";
 
 var rectElement = document.getElementById("rect1");
 var gElement = document.getElementById("g");
 var useElement = document.getElementById("use");
 var useElement2 = document.getElementById("usesymbol");
 var switchElement = document.getElementById("switch");
 var imgElement = document.getElementById("img");
 description("Test whether focusin and focusout events are dispatched and seen in the focusin/focusout event handlers: ");
@@ skipping 31 matching lines @@
 imgElement.setAttribute("onfocusout", "focusoutHandler(evt)");
 
 function clickAt(x, y)
 {
     eventSender.mouseMoveTo(x, y);
     eventSender.mouseDown();
     eventSender.mouseUp();
 }
 
 if (window.eventSender) {
+    // Mouse events only work after an initial layout
+    document.documentElement.offsetLeft;
 
     // cause focusin and focusout
     clickAt(50, 50);
     clickAt(150, 250);
     shouldBeEqualToString('focusinSeen', 'rect1');
     shouldBeEqualToString('focusoutSeen', 'rect1');
 
     clearFocusSeen();
 
     // cause focusin and focusout
@@ skipping 34 matching lines @@
     shouldBeEqualToString('focusinSeen', 'img');
     shouldBeEqualToString('focusoutSeen', 'img');
 
     successfullyParsed = true;
     successfullyParsed = true;
 
     if (window.testRunner)
         testRunner.notifyDone();
 } else
     alert("This test must be run via DRT!");