[JSDoc] Add annotations

Bulk-add JSDoc annotations, WTD-1482.

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

@@ -34,6 +34,7 @@ define(
          * Note that arguments here are meant to match those expected
          * by `Array.prototype.map`
          *
+         * @memberof platform/features/layout
          * @constructor
          * @param element the fixed position element, as stored in its
          *        configuration
@@ -50,6 +51,7 @@ define(
              * @memberof BoxProxy
              * @param {string} fill the new fill color
              * @returns {string} the fill color
+             * @memberof platform/features/layout.BoxProxy#
              */
             proxy.fill = new AccessorMutator(element, 'fill');
 
@@ -58,4 +60,4 @@ define(
 
         return BoxProxy;
     }
-);
+);