PR# 15232 Loop variants mess up debugger step-through

The step-through arrow in the feature pane while debugging gives misleading trace location inside of loops with loops variants.

Use the loop:
from
i := 1
until
i > 100
loop
i := i + 1
variant
1000 - i
end

As you step through it, the value for i won't change when stepping over "i := i + 1".  When stepping over "1000 - i" the value of i will then increase.

Fixed by rev#77602

Since the debugger supports "from invariant variant until loop end" order, we force the feature flat view to display this order, even if the loop was declared as "from invariant until loop variant end"

Later, the debugger should fully support both syntax, but at least, now the display and execution cursor are coherant during debugging.