Don't force layout for mouse event hit tests

LayoutTests/fast/images/script-tests/imagemap-dynamic-area-updates.js

 description("Test that when image map areas have their shape or coordinate dynamically altered, the clickable region changes.");
 
 if (!window.eventSender)
     debug("This test will only work properly inside DRT.");
 
 var image = document.createElement('img');
 image.setAttribute('usemap', '#m');
 image.style.width = '400px';
 image.style.height = '400px';
 image.style.border = '1px solid red';
 image.style.position = 'absolute';
 image.style.left = '0';
 image.style.top = '0';
 
 area = document.createElement('area');
 area.setAttribute('href', '#');
 area.setAttribute('onclick', 'areaClicked = true; return false;');
 
 areaClicked = false;
 
 var map = document.createElement('map');
 map.setAttribute('name', 'm');
 map.appendChild(area);
 
 document.body.appendChild(image);
 document.body.appendChild(map);
 
+// Mouse events only work after an initial layout
+document.body.offsetLeft;
+
 function setArea(shape, coords)
 {
     area.setAttribute('shape', shape);
     area.setAttribute('coords', coords);
 }
 
 function checkForArea(x, y)
 {
     if (!window.eventSender)
         return false;
@@ skipping 23 matching lines @@
 shouldBe("setArea('circle', '300, 300, 50'); checkForArea(300, 300)", "true");
 shouldBe("setArea('circle', '300, 300, 50'); checkForArea(320, 300)", "true");
 
 shouldBe("setArea('poly', '100, 100, 200, 100, 200, 200'); checkForArea(150, 150)", "true");
 shouldBe("setArea('poly', '100, 100, 200, 100, 200, 200'); checkForArea(100, 150)", "false");
 shouldBe("setArea('poly', '100, 100, 200, 100, 200, 200'); checkForArea(300, 300)", "false");
 
 shouldBe("setArea('default', ''); checkForArea(300, 300)", "true");
 
 document.body.removeChild(image);