[Tracking Requested - why for this release]: Regression in common user-facing UI. BUILD: Current trunk Mac build STEPS TO REPRODUCE: 1) Load data:text/html,<select><option>click and release me; you should see the dropdown stay dropped down<option>Another option 2) Follow the instructions in the testcase. ACTUAL RESULTS: As soon as I let go of the mouse button, the dropdown closes. I get all confused about why I can't select my options. EXPECTED RESULTS: The dropdown should stay open. That's what happens in Safari and Chrome, and with OS-native dropdowns ADDITIONAL INFORMATION: The regression range on nightlies is https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=f13e90d496cf1bc6dfc4fd398da33e4afe785bde&tochange=783356f1476eafd8e4d6fa5f3919cf6167e84f8d and I'm on Mac, so I bet this regressed with bug 430745.
updating fx52 status flag per https://bugzilla.mozilla.org/show_bug.cgi?id=1316597#c7