Return after errCB

Not returning after calling errCB in DOMPostProcessor was proceeding
with the parse.

Fixes the recurring errors here:
https://gist.github.com/gwicke/8e60d325468c874390d7

Change-Id: I93ff64d963b1d5e7e53d225d3e20778bbd899069
Merge "Return after errCB"