This change enables the trimmed ASTs behavior and fixes the broken
tests by caching parse errors along with the ASTs that are being reused.
Change-Id: Ia8e7cdb138c62a8be88659f801506e03f213fe8c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/181357
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Ian Cottrell <iancottrell@google.com>