Reorganize file structure

src/polyfills/performancePolyfill.spec.ts

@@ -0,0 +1,7 @@
+import { monotonicTime } from "./performancePolyfill";
+
+describe("Check performance.now polyfill", () => {
+    it("monotonicTime should return number", () => {
+        expect(typeof monotonicTime()).toEqual("number");
+    });
+});

src/polyfills/performancePolyfill.ts

@@ -0,0 +1,20 @@
+
+function makeMonotonicTime(): () => number {
+    if (typeof performance !== "undefined" && performance) {
+        let nowFun = performance.now  ||
+            performance.webkitNow     ||
+            performance.mozNow        ||
+            performance.oNow          ||
+            performance.msNow;
+
+        if (nowFun) {
+            return nowFun.bind(performance);
+        } else {
+            return Date.now;
+        }
+    } else {
+        return Date.now;
+    }
+}
+
+export const monotonicTime = makeMonotonicTime();