Update Angular 1.6 externs to accept !Object in JSONP call, for trusted types

Follows angular/angular.js#15161

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Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=152795936

Author: rjamet

contrib/externs/angular-1.6.js

@@ -1638,7 +1638,7 @@ angular.$http.prototype.get = function(url, opt_config) {};
 angular.$http.prototype.head = function(url, opt_config) {};
 
 /**
- * @param {string} url
+ * @param {string|!Object} url
  * @param {angular.$http.Config=} opt_config
  * @return {!angular.$http.HttpPromise}
  */