streams: Correct spinner bug when subscribing.
streams: Correct spinner bug when subscribing.

When clicking on the tick to subscribe to a stream,
an error occurred while trying to find the spinner
location because there are two DOM elements with the
same class, sub_unsub_button, and this made the
selector get the subscribe/unsubscribe button instead
the correct stream_row, where the tick is.

We now check whether the tick or the subscribe/unsubscribe
button was clicked, and if it was the last one we make
sure the stream_row and not the button is being passed
to the sub_or_unsub function.

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