The methods are now, `GetConstFrameSelection()` etc, but does not return
`const nsFrameSelection*`. I believe that `GetIndependentFrameSelection()` is
clearer than the old names.
And also this patch adds `IsIndependentSelection()` and
`GetIndependentSelectionRootParentElement()` to make some callers of
`GetLimiter()` easier to read.
For the consistency, `GetLimiter()` should be renamed too, but I already have
a patch doing it in bug 1954020 and it's bigger. Therefore, I leave it as-is
for now.
Differential Revision: https://phabricator.services.mozilla.com/D241774
80089dd884