Fix not rewriting else-if blocks. We would miss expanding the else-if clauses in a chain of selection statements. BUG=346463 BUG=391697 Change-Id: Iee644b875cf68d0ed3dc0b73542efc49ecb23242 Reviewed-on: https://chromium-review.googlesource.com/206822 Reviewed-by: Nicolas Capens <capn@chromium.org> Tested-by: Jamie Madill <jmadill@chromium.org> Reviewed-by: Shannon Woods <shannonwoods@chromium.org>