webView: narrow to topic on clicking headers in stream narrow. (#1646)
webView: narrow to topic on clicking headers in stream narrow. (#1646)

Fix: #1645
kunall17/zulip-mobile,kunall17/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,vishwesh3/zulip-mobile,kunall17/zulip-mobile,kunall17/zulip-mobile,vishwesh3/zulip-mobile