css: Use SCSS nesting in reactions.scss for `.message_reactions`.
css: Use SCSS nesting in reactions.scss for `.message_reactions`.

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