cue: remove FileSet from API

Change-Id: Idc52c4a07cc2ddfaaa217b30050a14e14584655d
Reviewed-on: https://cue-review.googlesource.com/c/cue/+/2123
Reviewed-by: Marcel van Lohuizen <mpvl@google.com>
diff --git a/internal/third_party/yaml/decode_test.go b/internal/third_party/yaml/decode_test.go
index 2e2122d..71cbf3c 100644
--- a/internal/third_party/yaml/decode_test.go
+++ b/internal/third_party/yaml/decode_test.go
@@ -13,7 +13,6 @@
 
 	"cuelang.org/go/cue/ast"
 	"cuelang.org/go/cue/format"
-	"cuelang.org/go/cue/token"
 	"cuelang.org/go/internal/third_party/yaml"
 )
 
@@ -624,8 +623,6 @@
 	C int
 }
 
-var fset = token.NewFileSet()
-
 func cueStr(node ast.Node) string {
 	if s, ok := node.(*ast.StructLit); ok {
 		node = &ast.File{
@@ -638,7 +635,7 @@
 }
 
 func newDecoder(t *testing.T, data string) *yaml.Decoder {
-	dec, err := yaml.NewDecoder(fset, "test.yaml", strings.NewReader(data))
+	dec, err := yaml.NewDecoder("test.yaml", strings.NewReader(data))
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -646,7 +643,7 @@
 }
 
 func callUnmarshal(t *testing.T, data string) (ast.Expr, error) {
-	return yaml.Unmarshal(fset, "test.yaml", []byte(data))
+	return yaml.Unmarshal("test.yaml", []byte(data))
 }
 
 func TestUnmarshal(t *testing.T) {
@@ -806,7 +803,7 @@
 			if err != nil {
 				t.Fatal(err)
 			}
-			expr, err := yaml.Unmarshal(fset, "test.yaml", mergeTests)
+			expr, err := yaml.Unmarshal("test.yaml", mergeTests)
 			if err != nil {
 				t.Fatal(err)
 			}