[Fixed Position] Fill in specs for selection proxies

Fill in specs for fixed position views selection proxies,
WTD-879.

platform/features/layout/test/elements/ElementProxySpec.js

@@ -6,7 +6,36 @@ define(
         "use strict";
 
         describe("A fixed position element proxy", function () {
+            var testElement,
+                testElements,
+                proxy;
 
+            beforeEach(function () {
+                testElement = {
+                    x: 1,
+                    y: 2,
+                    z: 3,
+                    width: 42,
+                    height: 24
+                };
+                testElements = [ {}, {}, testElement, {} ];
+                proxy = new ElementProxy(
+                    testElement,
+                    testElements.indexOf(testElement),
+                    testElements
+                );
+            });
+
+            it("exposes element properties", function () {
+                Object.keys(testElement).forEach(function (k) {
+                    expect(proxy[k]()).toEqual(testElement[k]);
+                });
+            });
+
+            it("allows elements to be removed", function () {
+                proxy.remove();
+                expect(testElements).toEqual([{}, {}, {}]);
+            });
         });
     }
 );