Add sysexEnabled readonly attribute to MIDIAccess

LayoutTests/webmidi/requestmidiaccess.html

Index: LayoutTests/webmidi/requestmidiaccess.html
diff --git a/LayoutTests/webmidi/requestmidiaccess.html b/LayoutTests/webmidi/requestmidiaccess.html
index 90c6fcefe4ad1cc6fb1276ba765a1c6de40a8fec..1a549ffbddb08d8f5290cac40af7b3a4755b2c83 100644
--- a/LayoutTests/webmidi/requestmidiaccess.html
+++ b/LayoutTests/webmidi/requestmidiaccess.html
@@ -18,6 +18,10 @@ function successCallback1(a) {
     shouldBe("access.inputs().length", "1");
     shouldBe("access.outputs().length", "1");
 
+    // Validate the values of the attributes on the access.
+    shouldBeDefined("access.sysexEnabled");
+    shouldBe("access.sysexEnabled", "false");

[tkent, 2014/03/24 11:52:38]

Use shouldBeFalse.

+
     var inputs = access.inputs();
     var outputs = access.outputs();
     var input = inputs[0];