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Also standardised alt text display between inbox and the blocktype
as the block lacked alt text, but leaving it off would have
left the block in state where the icons had no alt text. Unread
icons would not be differentiated from read icons for screenreaders

Change-Id: Ifaa88c45fef3dd0c5948e37ad120787607e3fd73
Signed-off-by: Melissa Draper <melissa@catalyst.net.nz>