MouseEvent.offsetX/Y should just return 0,0 for simulated clicks.

LayoutTests/fast/events/relative-offset-of-simulated-click-expected.txt

Index: LayoutTests/fast/events/relative-offset-of-simulated-click-expected.txt
diff --git a/LayoutTests/fast/events/relative-offset-of-simulated-click-expected.txt b/LayoutTests/fast/events/relative-offset-of-simulated-click-expected.txt
new file mode 100644
index 0000000000000000000000000000000000000000..6a83fe18a12424401477995bd1397599619d7874
--- /dev/null
+++ b/LayoutTests/fast/events/relative-offset-of-simulated-click-expected.txt
@@ -0,0 +1,18 @@
+This test documents the behavior of MouseEvent.offsetX/Y in response to HTMLElement.click().
+
+On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE".
+
+
+Simulated click with .click():
+PASS event.offsetX is 0
+PASS event.offsetY is 0
+Click with mouse at 0,0:
+PASS event.offsetX is 0
+PASS event.offsetY is 0
+Click with mouse at 40,50:
+PASS event.offsetX is 40
+PASS event.offsetY is 50
+PASS successfullyParsed is true
+
+TEST COMPLETE
+