ebitenutil: Add ReadSeekCloser and use this

ebitenutil/file.go

@@ -17,13 +17,12 @@
 package ebitenutil
 
 import (
-	"io"
 	"os"
 )
 
 // OpenFile opens a file and returns a stream for its data.
 //
 // This function is available both on desktops and browsers.
-func OpenFile(path string) (io.ReadCloser, error) {
+func OpenFile(path string) (ReadSeekCloser, error) {
 	return os.Open(path)
 }

ebitenutil/file_js.go

@@ -20,7 +20,6 @@ import (
 	"bytes"
 	"errors"
 	"fmt"
-	"io"
 
 	"github.com/gopherjs/gopherjs/js"
 )
@@ -33,7 +32,7 @@ func (f *file) Close() error {
 	return nil
 }
 
-func OpenFile(path string) (io.ReadCloser, error) {
+func OpenFile(path string) (ReadSeekCloser, error) {
 	var err error
 	var content *js.Object
 	ch := make(chan struct{})

ebitenutil/io.go

@@ -0,0 +1,24 @@
+// Copyright 2016 Hajime Hoshi
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package ebitenutil
+
+import (
+	"io"
+)
+
+type ReadSeekCloser interface {
+	io.ReadSeeker
+	io.Closer
+}