The dev toolbar is broken in dev-master, it gives error:

Block "menu" on template "@WebProfiler/Profiler/base.html.twig" does not exist in @WebProfiler/Profiler/base.html.twig at line 17.

that happens only when using:

"symfony/symfony": "dev-master",

problem is not there using:

"symfony/symfony": "~3.2.0",