RN: Fixed performanceNow() to allow debugging in Chrome

Summary:
Discovered when debugging a React Native app in Chrome. The function `performanceNow` was recently changed, so that in Chrome it now refers to `performance.now()` method. However, `now()` cannot be called standalone without a context.

Reproduced by a synthetic example in Chrome:
```
const performanceNow = window.performance.now;
performanceNow();

Uncaught TypeError: Illegal invocation
    at <anonymous>:1:1
```

Changelog:
[General] [Fixed] - Fix failure when debugging code in a browser; was caused by `performanceNow()` function.

Reviewed By: cpojer

Differential Revision: D22739176

fbshipit-source-id: f89b8a215b7b4c430ffd72a1d23539c4f1b31d24

Libraries/Utilities/createPerformanceLogger.js

@@ -13,7 +13,8 @@
 const Systrace = require('../Performance/Systrace');
 
 const infoLog = require('./infoLog');
-const performanceNow = global.nativeQPLTimestamp ?? global.performance.now;
+const performanceNow =
+  global.nativeQPLTimestamp ?? global.performance.now.bind(global.performance);
 
 type Timespan = {
   description?: string,