css: Limit message_failed class to inside message_controls.
css: Limit message_failed class to inside message_controls.

This is mostly for readability.

andersk/zulip,zulip/zulip,rht/zulip,rht/zulip,hackerkid/zulip,timabbott/zulip,tommyip/zulip,tommyip/zulip,rht/zulip,zulip/zulip,synicalsyntax/zulip,timabbott/zulip,hackerkid/zulip,rishig/zulip,eeshangarg/zulip,zulip/zulip,rishig/zulip,hackerkid/zulip,tommyip/zulip,brainwane/zulip,tommyip/zulip,andersk/zulip,hackerkid/zulip,showell/zulip,rishig/zulip,punchagan/zulip,tommyip/zulip,eeshangarg/zulip,eeshangarg/zulip,showell/zulip,tommyip/zulip,synicalsyntax/zulip,synicalsyntax/zulip,rishig/zulip,showell/zulip,shubhamdhama/zulip,rht/zulip,shubhamdhama/zulip,synicalsyntax/zulip,rht/zulip,rishig/zulip,showell/zulip,zulip/zulip,punchagan/zulip,kou/zulip,brainwane/zulip,showell/zulip,brainwane/zulip,rishig/zulip,andersk/zulip,andersk/zulip,eeshangarg/zulip,brainwane/zulip,kou/zulip,punchagan/zulip,showell/zulip,zulip/zulip,brainwane/zulip,shubhamdhama/zulip,andersk/zulip,shubhamdhama/zulip,zulip/zulip,kou/zulip,timabbott/zulip,punchagan/zulip,eeshangarg/zulip,timabbott/zulip,shubhamdhama/zulip,zulip/zulip,timabbott/zulip,synicalsyntax/zulip,kou/zulip,eeshangarg/zulip,shubhamdhama/zulip,brainwane/zulip,punchagan/zulip,synicalsyntax/zulip,timabbott/zulip,punchagan/zulip,synicalsyntax/zulip,kou/zulip,andersk/zulip,rishig/zulip,hackerkid/zulip,tommyip/zulip,kou/zulip,rht/zulip,andersk/zulip,shubhamdhama/zulip,hackerkid/zulip,rht/zulip,punchagan/zulip,showell/zulip,timabbott/zulip,kou/zulip,brainwane/zulip,eeshangarg/zulip,hackerkid/zulip