CVE-2018-9987: Fix XSS issue with muting notifications.
CVE-2018-9987: Fix XSS issue with muting notifications.

This fixes an XSS issue with Zulip's muting UI, where if a stream or
topic name contained malicious HTML containing JavaScript, and the
user did a muting interaction, the malicious JavaScript could run when
rendering the "you just muted a topic" notification.

We did an audit for similarly problematic use of `.html`, and found
none; for the next release we'll be merging a series of changes to our
linter to prevent future instances of this being added.

Thanks to Suhas Sunil Gaikwad for reporting this issue.

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