Revert "[EFL][WK2] Never create WebCore scrollbars for EFL/WK2"

This reverts commit 373d3d52252ea44fdd5d17635459d18d3d4b3e94.

Allow FrameViews to have hidden Scrollbars. This fixes key event scrolling
in fixed layout mode.

Task-number: QTBUG-34203
Change-Id: Idf157d51e01ba4d831e62d1e24f7283030c8e177
Reviewed-by: Michael Bruning <michael.bruning@digia.com>
Reviewed-by: Jocelyn Turcotte <jocelyn.turcotte@digia.com>