Previously, on Android devices, when the gr-reply-dialog overlay is opene, important contents could get cut off, including the submit and cancel buttons. This change makes the reply dialog scrollable and full width on small screens. The max-height is also 100% so if scrolling is required, the overlay will appear full screen. Bug: Issue 4944 Change-Id: Ibf265a3039129363e479cbb3c29cb887aa23d889