Bug 950225 - Prevent the click event pass the under panel.

Hi Gareth,

We do workaround here.
Because the click event just pass through the "create-account-view" panel to the under panel
with unknown reasons, then the bug is happened.
It might be a Gecko issue.

And the bug is just happened in real device not b2g-desktop or nightly.
So we do need to have marionette tests for it on b2g-desktop.

If we want to fix the issue without any workaround, we might fix it in Gecko not in Gaia.
But I think we could fix it in workaround way, and file a follow up bug for the possible gecko issue.

So please help me review the patch.
Thanks.