fix(closure): add type definition for Scope#$watchCollection

Closes angular#5475

Author: oojerryoo

closure/angular.js

@@ -762,7 +762,9 @@ angular.Module.requires;
  *   $parent: angular.Scope,
  *   $root: angular.Scope,
  *   $watch: function(
- *       (string|Function), (string|Function)=, boolean=):function()
+ *       (string|Function), (string|Function)=, boolean=):function(),
+ *   $watchCollection: function(
+ *       (string|Function), (string|Function)=):function()
  *   }}
  */
 angular.Scope;
@@ -834,6 +836,13 @@ angular.Scope.$root;
  */
 angular.Scope.$watch = function(exp, opt_listener, opt_objectEquality) {};
 
+/**
+ * @param {string|Function} exp
+ * @param {(string|Function)=} opt_listener
+ * @return {function()}
+ */
+angular.Scope.$watchCollection = function(exp, opt_listener) {};
+
 /**
  * @typedef {{
  *   currentScope: angular.Scope,