OpenFileWithContent is identical to CreateBuffer. Delete it in favor of
the latter, which (in my opinion) has the clearer name.
Change-Id: Icf0f017a9a71a273ace6d697c7d669a2df2e3ba8
Reviewed-on: https://go-review.googlesource.com/c/tools/+/263206
Run-TryBot: Robert Findley <rfindley@google.com>
gopls-CI: kokoro <noreply+kokoro@google.com>
TryBot-Result: Go Bot <gobot@golang.org>
Reviewed-by: Rebecca Stambler <rstambler@golang.org>
Trust: Robert Findley <rfindley@google.com>