[Browse] Begin implementing splitter movement

Begin implementing moveable splitter, WTD-747.

platform/commonUI/general/src/controllers/SplitPaneController.js

@@ -0,0 +1,36 @@
+/*global define*/
+
+define(
+    [],
+    function () {
+        "use strict";
+
+        function SplitPaneController() {
+            var minimum = 8,
+                maximum = 600,
+                current = 200,
+                style;
+
+            function updateStyle() {
+                style = { left: current + 'px' };
+            }
+
+            updateStyle();
+
+            return {
+                style: function () {
+                    return style;
+                },
+                move: function (delta) {
+                    current = Math.min(
+                        maximum,
+                        Math.max(minimum, current + delta)
+                    );
+                    updateStyle();
+                }
+            };
+        }
+
+        return SplitPaneController;
+    }
+);