Broke a.go into a few files (no real logic to it). These tests could be
categorized better, but it's a good start just to break up that huge
golden file.
Change-Id: I2c173f11ea2766e9232e3ec838c16f535cbee788
Reviewed-on: https://go-review.googlesource.com/c/tools/+/253279
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Robert Findley <rfindley@google.com>