tst_qtjson: Mark some test as XFAIL on BlackBerry 10

These tests seem to fail because denormalized numbers are not
supported on QNX yet, so marking them as expected failures.

 - testNumbers_2()
 - toJsonLargeNumericValues()
 - parseNumbers()

Task-number: QTBUG-37066
Change-Id: Ifec95b936fb70253395dee4d1ca18e85870486a3
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
tst_qnumeric: Mark some tests as XFAIL on BlackBerry 10

These tests seem to fail because denormalized numbers are not
supported on QNX yet, so marking them as expected failures.

 - floatDistance(denormal)
 - floatDistance_double(denormal)

Task-number: QTBUG-37094
Change-Id: I79dbc78da6e9bef8466264fd2cab4af0ee8b868f
Reviewed-by: Fabian Bumberger <fbumberger@rim.com>
Make QTreeView::expand/collapse check for ineffectual invocations

Added checks if item is already expanded/collapsed to
QTreeView::expand/collapse since the following computations
can be quite expensive. (This is useful when saving/restoring a
lot of item expansion state e.g. after a model reset.)

Task-number: QTBUG-35939
Change-Id: I82c4489f9fe0b8ac61994652a60312e34c46f628
Reviewed-by: Stephen Kelly <stephen.kelly@kdab.com>