This allows for multi-line comments where a new line is allowed between
expectations.
It also allows trailing new lines and commas in expectation lists.
Change-Id: I714f8ad483a0238281f26ceb74ce9e73d922af69
Reviewed-on: https://go-review.googlesource.com/c/151718
Reviewed-by: Rebecca Stambler <rstambler@golang.org>