Also add forced layouts to a new test

LayoutTests/fast/forms/file/input-file-re-render.html

Index: LayoutTests/fast/forms/file/input-file-re-render.html
diff --git a/LayoutTests/fast/forms/file/input-file-re-render.html b/LayoutTests/fast/forms/file/input-file-re-render.html
index d11ea8eb26c9304003f9da3d6bc5293c83d3ccba..8050e1dd5e7fd392acb7cb2de4182c0aeb28d899 100644
--- a/LayoutTests/fast/forms/file/input-file-re-render.html
+++ b/LayoutTests/fast/forms/file/input-file-re-render.html
@@ -11,6 +11,9 @@ function startTest()
 {
     var input = document.getElementById('file');
 
+    // Mouse events only work after an initial layout
+    document.body.offsetLeft;
+
     // Drop 2 files to the control.
     eventSender.beginDragWithFiles(['input-file-re-render.html', 'script-tests/TEMPLATE.html']);
     eventSender.mouseMoveTo(10, 10);