billing: Use on(click) instead of click handler.
billing: Use on(click) instead of click handler.

Makes it easy to get the click handler in node tests.

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