Never clone Group objects

Author: thiemowmde

src/Group.js

@@ -81,8 +81,7 @@ $.extend( SELF.prototype, {
 	 * @return {*}
 	 */
 	getItemContainer: function() {
-		// Do not allow altering the encapsulated container.
-		return new this._GroupableCollectionConstructor( this._groupableCollection.toArray() );
+		return this._groupableCollection;
 	},
 
 	/**
@@ -101,10 +100,7 @@ $.extend( SELF.prototype, {
 			}
 		}
 
-		// Clone the container to prevent manipulation of the items using the original container.
-		this._groupableCollection = new this._GroupableCollectionConstructor(
-			groupableCollection.toArray()
-		);
+		this._groupableCollection = groupableCollection;
 	},
 
 	/**

tests/Group.tests.js

@@ -177,8 +177,8 @@ QUnit.test( 'setItemContainer() & getItemContainer()', function( assert ) {
 		newContainer = getTestContainer( 'key', 3 );
 
 	assert.ok(
-		group.getItemContainer() !== container,
-		'Not returning original container.'
+		group.getItemContainer() === container,
+		'Returning original container.'
 	);
 
 	assert.ok(