[Forms] Add Locator control

Add Locator form control, to allow selection of a
destination for newly-created domain objects in a
tree. WTD-593.

platform/commonUI/browse/src/creation/LocatorController.js

@@ -0,0 +1,39 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        "use strict";
+
+        /**
+         * Controller for the "locator" control, which provides the
+         * user with the ability to select a domain object as the
+         * destination for a newly-created object in the Create menu.
+         * @constructor
+         */
+        function LocatorController($scope) {
+            // Populate values needed by the locator control. These are:
+            // * rootObject: The top-level object, since we want to show
+            //               the full tree
+            // * treeModel: The model for the embedded tree representation,
+            //              used for bi-directional object selection.
+            function setLocatingObject(domainObject) {
+                var context = domainObject &&
+                    domainObject.getCapability("context");
+
+                $scope.rootObject = context && context.getRoot();
+                $scope.treeModel.selectedObject = domainObject;
+                $scope.ngModel[$scope.field] = domainObject;
+            }
+
+            // Initial state for the tree's model
+            $scope.treeModel =
+                { selectedObject: $scope.ngModel[$scope.field] };
+
+            // Watch for changes from the tree
+            $scope.$watch("treeModel.selectedObject", setLocatingObject);
+        }
+
+        return LocatorController;
+    }
+);