[INTERNAL][FIX] sap.ui.require: work around PhantomJS bug 
[INTERNAL][FIX] sap.ui.require: work around PhantomJS bug 

In some Promise-heavy scenarios (e.g. RtaIntegration.qunit.html), calls
to sap.ui.require() never invoked the callback function although all
dependencies had been loaded. After some console-debugging, failing 
setTimeout calls have been identified as root cause. No timer was 
registered, no timer ID was returned (setTimeout returned 'undefined').
Slight, but non-trivial modifications to the code surrounding the
setTimeout() call made the problem disappear. This suggest that some 
bug in code optimization caused the issue, but no pattern could be
identified.

The code modification implemented by this change should be
minimally-invasive, but also should be easily recognizable as 'PhantomJS
specific'.

This is a very ugly bug that might appear in other, non-predictable
scenarios as well. Best way to fix it will be to replace PhantomJS with
a more robust approach for headless testing.

Change-Id: I50a4e508e0a691e8af98421df5c14beed47f4a6e

SAP/openui5,cschuff/openui5,nzamani/openui5,nzamani/openui5,cschuff/openui5,SAP/openui5,SAP/openui5,cschuff/openui5,nzamani/openui5,SAP/openui5