Use a unique variable name in activate heartbeat JS.

The name 'firstrow' was colliding with the "What's new" JS.

Props andemann.
Fixes #6003.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9129 cdf35c40-ae34-48e0-9cc9-0c9da1808c22
Pass current group ID to `BP_Group_Extension::display()`.

This creates greater parity with the other display methods in the class.

Props fahmiadib.
Fixes #5533.

git-svn-id: https://buddypress.svn.wordpress.org/trunk@9130 cdf35c40-ae34-48e0-9cc9-0c9da1808c22