Add check for '.end-content-title' to force the end of content section in an...

Add check for '.end-content-title' to force the end of content section in an accordion. Fixes js error on mobile when the footer is appended inside of a content section.

b/28917925

Related CL (critique): cl/123138252

Staged:
https://android-dot-devsite.googleplex.com/preview/setup-sdk.html?hl=es

Change-Id: I4eb606c0205af2315896fc0587cc1c4c2502f282