Removing redundant styles for icon-only buttons

As pointed out in bug 48593 (patched by
813cedb0308da58f3a2a4dc8ebefe489bf3005bc), these style rules are
overwritten later in the file and ignored by browser.
This patch will remove them as they do not serve any purpose.

Bug: 51623
Change-Id: Ib8aed40238f53198f207d4e57d0ced54622ad9e2
Merge "Removing redundant styles for icon-only buttons"