Make WebMIDI use blink Promise.

LayoutTests/webmidi/requestmidiaccess.html

Index: LayoutTests/webmidi/requestmidiaccess.html
diff --git a/LayoutTests/webmidi/requestmidiaccess.html b/LayoutTests/webmidi/requestmidiaccess.html
index fcdd3bbf9a348c3998f3b4ab9aac339bbb7023ba..90c6fcefe4ad1cc6fb1276ba765a1c6de40a8fec 100644
--- a/LayoutTests/webmidi/requestmidiaccess.html
+++ b/LayoutTests/webmidi/requestmidiaccess.html
@@ -61,7 +61,7 @@ function successCallback1(a) {
     shouldThrow('output.send([0xf0, 0x45, 0xf7])');
 
     // Now test System Exclusive access - our test mock should not allow this type of access.
-    shouldNotThrow("navigator.requestMIDIAccess({sysex: true}).then(successCallback2, errorCallback2)");
+    navigator.requestMIDIAccess({sysex: true}).then(successCallback2, errorCallback2);
 }
 
 function errorCallback1(error) {
@@ -82,7 +82,7 @@ function errorCallback2(error) {
 window.jsTestIsAsync = true;
 
 // Test basic access, with no System Exclusive.
-shouldNotThrow("navigator.requestMIDIAccess().then(successCallback1, errorCallback1)");
+navigator.requestMIDIAccess().then(successCallback1, errorCallback1);
 
 </script>
 </body>