Roll IDL to Dartium37 (r181268)

modules/encryptedmedia/MediaKeys.idl

Index: modules/encryptedmedia/MediaKeys.idl
diff --git a/modules/encryptedmedia/MediaKeys.idl b/modules/encryptedmedia/MediaKeys.idl
index b1f76e6e126108ef3bfdb03cd5ab7059f35c10a6..a17d8d903ca274a8b197fc4664869553d5b0475a 100644
--- a/modules/encryptedmedia/MediaKeys.idl
+++ b/modules/encryptedmedia/MediaKeys.idl
@@ -26,10 +26,14 @@
 [
     RuntimeEnabled=EncryptedMedia,
     Constructor(DOMString keySystem),
+    ConstructorCallWith=ExecutionContext,
     RaisesException=Constructor,
-    WillBeGarbageCollected
+    GarbageCollected,
+    TypeChecking=Interface|Nullable
 ] interface MediaKeys {
+    readonly attribute DOMString keySystem;
+
     [CallWith=ExecutionContext, RaisesException] MediaKeySession createSession(DOMString type, Uint8Array initData);
 
-    readonly attribute DOMString keySystem;
+    static boolean isTypeSupported(DOMString keySystem, optional DOMString contentType = null);
 };