Added return type to Stopwatch::getSections()
minor #11067 [Stopwatch] Added return type to Stopwatch::getSections() (umpirsky)

This PR was merged into the 2.6-dev branch.

Discussion
----------

[Stopwatch] Added return type to Stopwatch::getSections()

https://github.com/symfony/symfony/pull/10851#discussion_r13479016

Commits
-------

ab00361 Added return type to Stopwatch::getSections()