internal/span: remove check for nil content

We should instead treat nil content as an empty file.

Change-Id: I45f1d1c9f3382d2ef7f6d9769c808fd871d603e3
Reviewed-on: https://go-review.googlesource.com/c/tools/+/252122
Run-TryBot: Rebecca Stambler <rstambler@golang.org>
Reviewed-by: Heschi Kreinick <heschi@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
diff --git a/internal/span/utf16.go b/internal/span/utf16.go
index 561b3fa..f06a246 100644
--- a/internal/span/utf16.go
+++ b/internal/span/utf16.go
@@ -15,9 +15,6 @@
 // This is used to convert from the native (always in bytes) column
 // representation and the utf16 counts used by some editors.
 func ToUTF16Column(p Point, content []byte) (int, error) {
-	if content == nil {
-		return -1, fmt.Errorf("ToUTF16Column: missing content")
-	}
 	if !p.HasPosition() {
 		return -1, fmt.Errorf("ToUTF16Column: point is missing position")
 	}
diff --git a/internal/span/utf16_test.go b/internal/span/utf16_test.go
index 0ae2749..1eae797 100644
--- a/internal/span/utf16_test.go
+++ b/internal/span/utf16_test.go
@@ -29,7 +29,7 @@
 	{
 		scenario: "cursor missing content",
 		input:    nil,
-		err:      "ToUTF16Column: missing content",
+		err:      "ToUTF16Column: point is missing position",
 	},
 	{
 		scenario: "cursor missing position",