[Common UI] Poll split pane position

Poll to position the splitter in an mct-split-pane, in
order to detect later style changes. #53.

platform/commonUI/general/bundle.json

@@ -135,7 +135,7 @@
             {
                 "key": "mctSplitPane",
                 "implementation": "directives/MCTSplitPane.js",
-                "depends": [ "$parse", "$log" ]
+                "depends": [ "$parse", "$log", "$interval" ]
             },
             {
                 "key": "mctSplitter",

platform/commonUI/general/src/directives/MCTSplitPane.js

@@ -28,6 +28,7 @@ define(
 
         // Pixel width to allocate for the splitter itself
         var DEFAULT_ANCHOR = 'left',
+            POLLING_INTERVAL = 15, // milliseconds
             CHILDREN_WARNING_MESSAGE = [
                 "Invalid mct-split-pane contents.",
                 "This element should contain exactly three",
@@ -94,7 +95,7 @@ define(
          * @memberof platform/commonUI/general
          * @constructor
          */
-        function MCTSplitPane($parse, $log) {
+        function MCTSplitPane($parse, $log, $interval) {
             var anchors = {
                 left: true,
                 right: true,
@@ -105,6 +106,7 @@ define(
             function controller($scope, $element, $attrs) {
                 var anchorKey = $attrs.anchor || DEFAULT_ANCHOR,
                     anchor,
+                    activeInterval,
                     positionParsed = $parse($attrs.position),
                     position; // Start undefined, until explicitly set
 
@@ -193,6 +195,16 @@ define(
                     $element.children().eq(anchor.reversed ? 2 : 0)[0]
                 ));
 
+                // And poll for position changes enforced by styles
+                activeInterval = $interval(function () {
+                    getSetPosition(getSetPosition());
+                }, POLLING_INTERVAL, false);
+
+                // ...and stop polling when we're destroyed.
+                $scope.$on('$destroy', function () {
+                    $interval.cancel(activeInterval);
+                });
+
                 // Interface exposed by controller, for mct-splitter to user
                 return {
                     position: getSetPosition,

platform/commonUI/general/src/directives/MCTSplitter.js

@@ -44,14 +44,11 @@ define(
          */
         function MCTSplitter() {
             function link(scope, element, attrs, mctSplitPane) {
-                var initialPosition;
+                var initialPosition,
+                    activeInterval;
 
                 element.addClass("splitter");
 
-                // Now that we have the above class, the splitter width
-                // will have changed, so trigger a positioning update.
-                mctSplitPane.position(mctSplitPane.position());
-
                 scope.splitter = {
                     // Begin moving this splitter
                     startMove: function () {