fix: reset referring_domain

Author: Mercy811

src/amplitude-client.js

@@ -761,6 +761,7 @@ AmplitudeClient.prototype._initUtmData = function _initUtmData(queryParams, cook
 AmplitudeClient.prototype._unsetUTMParams = function _unsetUTMParams() {
   var identify = new Identify();
   identify.unset(Constants.REFERRER);
+  identify.unset(Constants.REFERRING_DOMAIN);
   identify.unset(Constants.UTM_SOURCE);
   identify.unset(Constants.UTM_MEDIUM);
   identify.unset(Constants.UTM_CAMPAIGN);

src/constants.js

@@ -53,6 +53,7 @@ export default {
   AMP_REFERRER_PARAM: 'amp_referrer', // url param for overwriting the document.refer
 
   REFERRER: 'referrer',
+  REFERRING_DOMAIN: 'referring_domain',
 
   // UTM Params
   UTM_SOURCE: 'utm_source',

test/amplitude-client.js

@@ -3394,6 +3394,7 @@ describe('AmplitudeClient', function () {
         {
           $unset: {
             referrer: '-',
+            referring_domain: '-',
             utm_source: '-',
             utm_medium: '-',
             utm_campaign: '-',
@@ -3483,6 +3484,7 @@ describe('AmplitudeClient', function () {
         {
           $unset: {
             referrer: '-',
+            referring_domain: '-',
             utm_source: '-',
             utm_medium: '-',
             utm_campaign: '-',