[Fixed Position] Add fill properties

Add 'fill' properties, to allow specifying background
color in Fixed Position view. WTD-881.

platform/features/layout/src/elements/TextProxy.js

@@ -0,0 +1,28 @@
+/*global define*/
+
+define(
+    ['./BoxProxy', './AccessorMutator'],
+    function (BoxProxy, AccessorMutator) {
+        'use strict';
+
+        /**
+         * Selection proxy for Text elements in a fixed position view.
+         *
+         * Note that arguments here are meant to match those expected
+         * by `Array.prototype.map`
+         *
+         * @constructor
+         * @param element the fixed position element, as stored in its
+         *        configuration
+         * @param index the element's index within its array
+         * @param {Array} elements the full array of elements
+         */
+        function TextProxy(element, index, elements) {
+            var proxy = new BoxProxy(element, index, elements);
+
+            return proxy;
+        }
+
+        return TextProxy;
+    }
+);