Don't force layout for mouse event hit tests

LayoutTests/fast/forms/input-text-click-outside.html

Index: LayoutTests/fast/forms/input-text-click-outside.html
diff --git a/LayoutTests/fast/forms/input-text-click-outside.html b/LayoutTests/fast/forms/input-text-click-outside.html
index 2ed44f7c6dd8f0a237ee581b3afd2abf1ed9f81d..613e68e5dae8bf24530ff0b25495dd2ab5ce62e0 100644
--- a/LayoutTests/fast/forms/input-text-click-outside.html
+++ b/LayoutTests/fast/forms/input-text-click-outside.html
@@ -2,6 +2,8 @@
 <p>This test clicks outside an input element, and must not result in the element receiving focus. If the test succeeds the element should not have a focus ring.</p>
 <script>
 if (window.eventSender) {
+    // Mouse events only work after an initial layout
+    document.body.offsetLeft;
     eventSender.mouseMoveTo(200, 45);
     eventSender.mouseDown();
     eventSender.mouseUp();