[FIX] RenderManager: Make hidden placeholders identifyable in CSS

Invisible placeholders, rendered when a control has its visible
property set to false, now have the class "sapUiHiddenPlaceholder"
in addition to the "display: none" style attribute.

CR-Id: 012006153200015648832014
Change-Id: If59549bcef233536202f1e39225c4ef5bc04e071
[FIX] sap.m.Popover/Dialog: scrolling doesn't work property on Android
stock browser

Change-Id: Ib3a1ea99de754be19c608f23156e17ac923c02ac
CSS: 0120031469 0000704949 2014
CR-Id: 012006153200015733762014
Merge "[FIX] sap.m.Popover/Dialog: scrolling doesn't work property on Android stock browser" into rel-1.26
Merge "[FIX] RenderManager: Make hidden placeholders identifyable in CSS" into rel-1.26