Fix a number of issues with determining the type of stdio

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 38c488d1857070345f2796b21336caf916b4c378..941ae374af38f04c8c28d33354704039156be6bf 100644
--- a/runtime/bin/stdio_patch.dart
+++ b/runtime/bin/stdio_patch.dart
@@ -31,7 +31,11 @@ patch class _StdIOUtils {
   }
 
   static int _socketType(nativeSocket) {
-    return _getSocketType(nativeSocket);
+    var result = _getSocketType(nativeSocket);
+    if (result is OSError) {
+      throw new FileIOException("Error retreiving socket type", result);
+    }
+    return result;
   }
 }