Add getter for lineMode and echoMode for Stdin.

runtime/bin/stdio_patch.dart

Index: runtime/bin/stdio_patch.dart
diff --git a/runtime/bin/stdio_patch.dart b/runtime/bin/stdio_patch.dart
index eb9aa6893baf0c104fd9783a2773d2d665afba88..5d5cdaf7087a6b4aeac27e2ccf79952e5dea1ff4 100644
--- a/runtime/bin/stdio_patch.dart
+++ b/runtime/bin/stdio_patch.dart
@@ -41,8 +41,17 @@ patch class _StdIOUtils {
 
 patch class Stdin {
   /* patch */ int readByteSync() native "Stdin_ReadByte";
-  /* patch */ void set echoMode(bool enabled) native "Stdin_SetEchoMode";
-  /* patch */ void set lineMode(bool enabled) native "Stdin_SetLineMode";
+
+  /* patch */ bool get echoMode => _echoMode;
+  /* patch */ void set echoMode(bool enabled) { _echoMode = enabled; }
+
+  /* patch */ bool get lineMode => _lineMode;
+  /* patch */ void set lineMode(bool enabled) { _lineMode = enabled; }
+
+  static bool get _echoMode native "Stdin_GetEchoMode";
+  static void set _echoMode(bool enabled) native "Stdin_SetEchoMode";
+  static bool get _lineMode native "Stdin_GetLineMode";
+  static void set _lineMode(bool enabled) native "Stdin_SetLineMode";
 }