ENYO-549: VerticalGridDelegate doesn't trigger scroller remeasure

Issue:

enyo.VerticalDelgate (in its adjustBuffer() method) triggers the
list's scroller to measure its bounds after list pages have been
generated / regenerated. However, enyo.VerticalDelegate overrides
adjustBuffer() without calling the super method, so this
measurement doesn't occur.

Under some circumstances, this doesn't matter, since scroller
measurement is also triggered by other events (e.g. wheel
scrolling, starting a drag, etc.) – but it is problematic in other
cases (where there's a persistent, manipulatable scroll controller
like a draggable thumb; or when the list generates pages in the
middle of a long animated scroll).

Fix:

To fix, we'll just add the trigger to VerticalGridDelegate as well.

HorizontalDelegate.adjustBuffer() does call the super method, so no
need to add it explicitly in that case.

Enyo-DCO-1.1-Signed-Off-By: Gray Norton (gray.norton@lge.com)
Merge pull request #941 from enyojs/ENYO-549-graynorton

ENYO-549: VerticalGridDelegate doesn't trigger scroller remeasure

Reviewed-By: Blake Stephens (blake.stephens@lge.com)
Integrated-By: Aaron Tam (aaron.tam@lge.com)