util.enforce_arity takes a function and returns a new version which
throws an error if an incorrect number of arguments (as determined by
the function prototype) are passed.
(imported from commit 20e69a6dc7b6f8455726ab4fae8d5b7b04dc4103)
When you read messages in a narrow and then un-narrow, collapse
adjacent messages read in the narrow into a summary row that can
be clicked to expand those messages.
Scoped to staging with feature flags.
The implementation of this within our current MessageList is rather ugly.
(imported from commit bcb3a39d8c0c334136fe86318f18ead03f0f50bf)
Zev Benjamin
Kevin Mehall
Steve Howell
Zev Benjamin
Tim Abbott
Scott Feeney