internal/lsp/testdata: change test case to work around CL 202581
internal/lsp/testdata: change test case to work around CL 202581

go/parser has switched from reporting no position for the end of a
broken file to reporting an invalid position. This broke on of our tests
that contains broken code. Change the test case as a result.

Change-Id: I4feb7790539994e593c56d5ae84929364c1eec1c
Reviewed-on: https://go-review.googlesource.com/c/tools/+/204202
Run-TryBot: Rebecca Stambler <d7cf11e5f299d88ea8348366a9fc4f7c335c3afa@golang.org>
Reviewed-by: Ian Cottrell <52376736e5e84615ec49f9c1843b8acc178b1d8d@google.com>

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