Bug 1764560: Disable mochitest bug418986-3 on Windows-e10s r=bobowen

The test hasn't been working properly.  The timing of the IPDL message PBrowser::ChildToParentMatrix is often too late for the test -- it will have already computed and compared invalid "device" coordinates.  Disabling the test while we figure this out.

Differential Revision: https://phabricator.services.mozilla.com/D144318

dom/events/test/mochitest.ini

@@ -49,6 +49,7 @@ support-files = test_bug336682.js
 skip-if = toolkit == 'android' # android: TIMED_OUT
 [test_bug412567.html]
 [test_bug418986-3.html]
+skip-if = e10s && os == 'win' # bug 1764560
 [test_bug422132.html]
 [test_bug426082.html]
 [test_bug427537.html]