Vector: Remove backwards-compatible #bodyContent selector

The selector for #bodyContent was needed for a period of 31 days after
9c8592fe was deployed (i.e., until 1 June 2014), as cache breakage
avoidance from the switch to using .mw-body-content as the selector.

Change-Id: Id3e83fa9bc6188627c0e9e2290bf8594bf4298d8
Merge "Vector: Remove backwards-compatible #bodyContent selector"