Issue #2550981 by alexpott, stefan.r, davidhernandez, joelpittet, Wim Leers, xjm, josephdpurcell, akalata, dawehner: Remove SafeMarkup::set in FormErrorHandler::displayErrorMessages()

Issue #2505931 by stefan.r, akalata, cilefen, pwolanin, joelpittet, YesCT, alexpott, davidhernandez, larowlan, colbol, xjm, Wim Leers, dawehner, Cottser, catch: Remove SafeMarkup::set in ViewListBuilder

Issue #2422363 by mortendk, joelpittet, davidhernandez: Rewrite the menu CSS components inline with our CSS standards

Issue #2425691 by pjbaert, kepford, drupalninja99: Remove .leaf/.menu-item--leaf from menu CSS components

Revert "Issue #1842140 by mdrummond, tonystar, gavin.hughes, killerpoke, lauriii, droweski, stevector, omg-its-maggie, jenlampton, Renee S: Remove title and wrapper div from theme_item_list."

This reverts commit 79395676.

Issue #1842140 by mdrummond, tonystar, gavin.hughes, killerpoke, lauriii, droweski, stevector, omg-its-maggie, jenlampton, Renee S: Remove title and wrapper div from theme_item_list.