Make return type more specific for File.inputStream and File.outputStream, for String.byteInputStream

libraries/stdlib/src/kotlin/io/FileReadWrite.kt

@@ -190,14 +190,14 @@ public fun File.readLines(charset: String): List<String> = readLines(Charset.for
 /**
  * Constructs a new FileInputStream of this file and returns it as a result.
  */
-public fun File.inputStream(): InputStream {
+public fun File.inputStream(): FileInputStream {
     return FileInputStream(this)
 }
 
 /**
  * Constructs a new FileOutputStream of this file and returns it as a result.
  */
-public fun File.outputStream(): OutputStream {
+public fun File.outputStream(): FileOutputStream {
     return FileOutputStream(this)
 }
 

libraries/stdlib/src/kotlin/io/IOStreams.kt

@@ -44,7 +44,7 @@ public operator fun BufferedInputStream.iterator(): ByteIterator =
 
 
 /** Creates a new byte input stream for the string. */
-public fun String.byteInputStream(charset: Charset = Charsets.UTF_8): InputStream = ByteArrayInputStream(toByteArray(charset))
+public fun String.byteInputStream(charset: Charset = Charsets.UTF_8): ByteArrayInputStream = ByteArrayInputStream(toByteArray(charset))
 
 /**
  * Creates an input stream for reading data from this byte array.