[IMP] web: ajax service: ensure widget is alive

... before resolving/rejecting the deferred once the RPC is done.
Doing this in the ajax service is equal to wrap every rpc with
this.alive() in the former versions.

addons/web/static/src/js/core/mixins.js

@@ -456,7 +456,8 @@ var ServiceProvider = {
     },
     _call_service: function (event) {
         var service = this.services[event.data.service];
-        var result = service[event.data.method].apply(service, event.data.args);
+        var args = event.data.args.concat(event.target);
+        var result = service[event.data.method].apply(service, args);
         event.data.callback(result);
     },
 };

addons/web/static/src/js/services/ajax_service.js

@@ -6,8 +6,18 @@ var session = require('web.session');
 
 var AjaxService = AbstractService.extend({
     name: 'ajax',
-    rpc: function (route, args, options) {
-        return session.rpc(route, args, options);
+    rpc: function (route, args, options, target) {
+        return $.Deferred(function (def) {
+            session.rpc(route, args, options).then(function () {
+                if (!target.isDestroyed()) {
+                    def.resolve.apply(def, arguments);
+                }
+            }, function () {
+                if (!target.isDestroyed()) {
+                    def.reject.apply(def, arguments);
+                }
+            });
+        }).promise();
     },
 });