Add support for promise rejection tracking

Summary:
Adds support for tracking unhandled rejections with `console.warn` (= yellow box).

I will create a follow-up with proper error stack formatting.

related: facebook#4971
fixes: facebook#4045, facebook#4142

public

{F59857438}

{F59857439}

Reviewed By: bestander

Differential Revision: D2803126

fb-gh-sync-id: 376b33e42a967675a04338cbff3ec315a77d1037

Libraries/Promise.js

@@ -25,6 +25,26 @@
 global.setImmediate = require('setImmediate');
 var Promise = require('promise/setimmediate/es6-extensions');
 require('promise/setimmediate/done');
+if (__DEV__) {
+  require('promise/setimmediate/rejection-tracking').enable({
+    allRejections: true,
+    onUnhandled: (id, error) => {
+      const {message, stack} = error;
+      const warning =
+        `Possible Unhandled Promise Rejection (id: ${id}):\n` +
+        (message == null ? '' : `${message}\n`) +
+        (stack == null ? '' : stack);
+      console.warn(warning);
+    },
+    onHandled: (id) => {
+      const warning =
+        `Promise Rejection Handled (id: ${id})\n` +
+        'This means you can ignore any previous messages of the form ' +
+        `"Possible Unhandled Promise Rejection (id: ${id}):"`;
+      console.warn(warning);
+    },
+  });
+}
 
 /**
  * Handle either fulfillment or rejection with the same callback.