Correctly bind Touchable.js setTimeout

Summary:
Fixes #5337

`this.setTimeout` is undefined and the scope wasn't being passed through causing a RedBox error.
Closes #5376

Reviewed By: svcscm

Differential Revision: D2838623

Pulled By: androidtrunkagent

fb-gh-sync-id: 513210298b6c39d812047a03d8f2edd5c11e46f6

Libraries/Components/Touchable/Touchable.js

@@ -670,7 +670,7 @@ var TouchableMixin = {
       this.touchableHandleActivePressIn && this.touchableHandleActivePressIn(e);
     } else if (!newIsHighlight && curIsHighlight && this.touchableHandleActivePressOut) {
       if (this.touchableGetPressOutDelayMS && this.touchableGetPressOutDelayMS()) {
-        this.pressOutDelayTimeout = this.setTimeout(function() {
+        this.pressOutDelayTimeout = setTimeout(() => {
           this.touchableHandleActivePressOut(e);
         }, this.touchableGetPressOutDelayMS());
       } else {