[INTERNAL] sap.m.Dialog: QUnit test adjustment
[INTERNAL] sap.m.Dialog: QUnit test adjustment

The test was checking if the dialog is outside of the viewport,
by using jQuery(window).scrollTop(), which had wrong value due
to scrolling problems inside the test page.

Change-Id: I8683d206da00ef4a2e8e68654231346fe49f5fe1
BCP: 1980333134

SAP/openui5,SAP/openui5,SAP/openui5,SAP/openui5