Add line handler to string stream

runtime/bin/input_stream.dart

Index: runtime/bin/input_stream.dart
diff --git a/runtime/bin/input_stream.dart b/runtime/bin/input_stream.dart
index e9f496b66b2c0b847f153ce8d5eb40ea29d257cc..0f009a33a53069641b3f9edef9513a5ddf5ee51f 100644
--- a/runtime/bin/input_stream.dart
+++ b/runtime/bin/input_stream.dart
@@ -71,7 +71,8 @@ interface StringInputStream factory _StringInputStream {
   /**
    * Reads the next line from the stream. The line ending characters
    * will not be part og the returned string. If a full line is not
-   * available null will be returned.
+   * available null will be returned. The line break character(s) are
+   * discarded.
    */
   String readLine();
 
@@ -87,11 +88,20 @@ interface StringInputStream factory _StringInputStream {
   String get encoding();
 
   /**
-   * Sets the handler that gets called when data is available.
+   * Sets the handler that gets called when data is available. The two
+   * handlers [dataHandler} and [lineHandler] are mutually exclusive
+   * and setting one will remove the other.
    */
   void set dataHandler(void callback());
 
   /**
+   * Sets the handler that gets called when a line is available. The
+   * two handlers [dataHandler} and [lineHandler] are mutually
+   * exclusive and setting one will remove the other.
+   */
+  void set lineHandler(void callback());
+
+  /**
    * Sets the handler that gets called when there will be no more data
    * available in the stream.
    */