minor: Remove irrelevant comments in stream_edit.js.
minor: Remove irrelevant comments in stream_edit.js.

Remove comments in the module stream_edit.js that became
irrelevant after changes in commit 96e035a.

rht/zulip,eeshangarg/zulip,eeshangarg/zulip,zulip/zulip,hackerkid/zulip,andersk/zulip,andersk/zulip,punchagan/zulip,eeshangarg/zulip,kou/zulip,rht/zulip,kou/zulip,andersk/zulip,zulip/zulip,rht/zulip,kou/zulip,rht/zulip,zulip/zulip,andersk/zulip,rht/zulip,eeshangarg/zulip,hackerkid/zulip,punchagan/zulip,punchagan/zulip,zulip/zulip,andersk/zulip,andersk/zulip,kou/zulip,hackerkid/zulip,kou/zulip,hackerkid/zulip,eeshangarg/zulip,rht/zulip,zulip/zulip,zulip/zulip,kou/zulip,rht/zulip,zulip/zulip,andersk/zulip,hackerkid/zulip,punchagan/zulip,eeshangarg/zulip,punchagan/zulip,hackerkid/zulip,eeshangarg/zulip,hackerkid/zulip,punchagan/zulip,punchagan/zulip,kou/zulip