[Fixed Position] Add tests and fix checkstyle error.

Fixes #1496

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

@@ -67,6 +67,10 @@ define(
              */
             proxy.size = new AccessorMutator(element, 'size');
 
+            if (proxy.size() === undefined) {
+                proxy.size("13px");
+            }
+
             return proxy;
         }