go/expect: use parser.AllErrors when extracting Notes
go/expect: use parser.AllErrors when extracting Notes

Without this parser mode, go/parser will bail out and return no comments
from a parsed file if there are more than 10 errors. This can lead to
tests silently not running, as noted in the TODO right above the parse.

This can still happen: poor parser recovery could result in comments not
being parsed. However, the parser is generally pretty good about
preserving comments, and anyway passing parser.AllErrors means that
adding a single new error to a testdata file will not suddenly cause all
errors in that file to be ignored.

Change-Id: Ib3c22944999651018d38fa6ce5c5a11ac6853aa0
Reviewed-on: https://go-review.googlesource.com/c/tools/+/293932
Trust: Robert Findley <9179eee875d1ee628c37fb47d7e749e855ffd21f@google.com>
Run-TryBot: Robert Findley <9179eee875d1ee628c37fb47d7e749e855ffd21f@google.com>
gopls-CI: kokoro <2ac7b1f3fa578934c95181d4272be0d3bca00121@google.com>
TryBot-Result: Go Bot <66cb808b70d30c07676d5e946fee83fd561249e5@golang.org>
Reviewed-by: Heschi Kreinick <e89ab2b172855aa0ad01c40c4d8a3535a61ac68a@google.com>

golang/tools,golang/tools,golang/tools,golang/tools,golang/tools