Use requestMediaKeySystemAccess() to check type support in EME layout tests

LayoutTests/media/encrypted-media/encrypted-media-keystatuses-multiple-updates.html

Index: LayoutTests/media/encrypted-media/encrypted-media-keystatuses-multiple-updates.html
diff --git a/LayoutTests/media/encrypted-media/encrypted-media-keystatuses-multiple-updates.html b/LayoutTests/media/encrypted-media/encrypted-media-keystatuses-multiple-updates.html
index 45a25ab230e45a1525e05b20ff5ccd3ef6c6507d..812f60e36ee2db890f6fcfbf9b94db1c8784b364 100644
--- a/LayoutTests/media/encrypted-media/encrypted-media-keystatuses-multiple-updates.html
+++ b/LayoutTests/media/encrypted-media/encrypted-media-keystatuses-multiple-updates.html
@@ -58,10 +58,13 @@
                     }
                 }
 
-                navigator.requestMediaKeySystemAccess('org.w3.clearkey', [{}]).then(function(access) {
+                getInitDataType().then(function(type) {
+                    initDataType = type;
+                    initData = getInitData(initDataType);
+                    return navigator.requestMediaKeySystemAccess('org.w3.clearkey', [{}]);
+                }).then(function(access) {
                     return access.createMediaKeys();
                 }).then(function(mediaKeys) {
-                    var initDataType = getInitDataType();
                     mediaKeySession = mediaKeys.createSession();
 
                     // There should be no keys defined yet.
@@ -70,7 +73,7 @@
                     waitForEventAndRunStep('message', mediaKeySession, processMessage, test);
                     waitForEventAndRunStep('keystatuseschange', mediaKeySession, processKeyStatusesChange, test);
 
-                    return mediaKeySession.generateRequest(initDataType, getInitData(initDataType));
+                    return mediaKeySession.generateRequest(initDataType, initData);
                 }).catch(function(error) {
                     forceTestFailureFromPromise(test, error);
                 });