Implement WebIDL callback interfaces

This commit implements callback interfaces for WebIDL, the final WebIDL
construct that we were unconditionally ignoring! Callback interfaces are
implemented as dictionaries of callbacks. Single-operation callback interfaces
are also expanded when flattening to accept a `Function` as well, in accordance
with the WebIDL spec.

New features have been added to `web-sys` for all the new callback interface
types. Additionally the `EventTarget.webidl` was tweaked to not have
`EventListener?` as this is required for all functional usage and there's no
need to keep that sort of web browser compat here.

Closes #258

crates/web-sys/Cargo.toml

@@ -38,7 +38,10 @@ wasm-bindgen-futures = { path = '../futures', version = '0.2.21' }
 AbortController = []
 AbortSignal = []
 AddEventListenerOptions = []
+AesCbcParams = []
+AesCtrParams = []
 AesDerivedKeyParams = []
+AesGcmParams = []
 AesKeyAlgorithm = []
 AesKeyGenParams = []
 Algorithm = []
@@ -289,10 +292,12 @@ Element = []
 ElementCreationOptions = []
 ElementDefinitionOptions = []
 EndingTypes = []
+ErrorCallback = []
 ErrorEvent = []
 ErrorEventInit = []
 Event = []
 EventInit = []
+EventListener = []
 EventListenerOptions = []
 EventModifierInit = []
 EventSource = []
@@ -310,6 +315,7 @@ FetchReadableStreamReadDataArray = []
 FetchReadableStreamReadDataDone = []
 FetchState = []
 File = []
+FileCallback = []
 FileList = []
 FilePropertyBag = []
 FileReader = []
@@ -317,7 +323,9 @@ FileReaderSync = []
 FileSystem = []
 FileSystemDirectoryEntry = []
 FileSystemDirectoryReader = []
+FileSystemEntriesCallback = []
 FileSystemEntry = []
+FileSystemEntryCallback = []
 FileSystemFileEntry = []
 FileSystemFlags = []
 FillMode = []
@@ -602,6 +610,7 @@ NetworkCommandOptions = []
 NetworkInformation = []
 NetworkResultOptions = []
 Node = []
+NodeFilter = []
 NodeIterator = []
 NodeList = []
 Notification = []
@@ -611,6 +620,7 @@ NotificationEvent = []
 NotificationEventInit = []
 NotificationOptions = []
 NotificationPermission = []
+ObserverCallback = []
 OfflineAudioCompletionEvent = []
 OfflineAudioCompletionEventInit = []
 OfflineAudioContext = []
@@ -702,10 +712,13 @@ ProgressEventInit = []
 PromiseRejectionEvent = []
 PromiseRejectionEventInit = []
 PublicKeyCredential = []
+PublicKeyCredentialDescriptor = []
 PublicKeyCredentialEntity = []
 PublicKeyCredentialParameters = []
+PublicKeyCredentialRequestOptions = []
 PublicKeyCredentialRpEntity = []
 PublicKeyCredentialType = []
+PublicKeyCredentialUserEntity = []
 PushEncryptionKeyName = []
 PushEvent = []
 PushEventInit = []
@@ -768,6 +781,7 @@ RtcIceServer = []
 RtcIceTransportPolicy = []
 RtcIdentityAssertion = []
 RtcIdentityAssertionResult = []
+RtcIdentityProvider = []
 RtcIdentityProviderDetails = []
 RtcIdentityProviderOptions = []
 RtcIdentityValidationResult = []
@@ -1038,6 +1052,7 @@ VideoPlaybackQuality = []
 VideoStreamTrack = []
 VideoTrack = []
 VideoTrackList = []
+VoidCallback = []
 VrDisplay = []
 VrDisplayCapabilities = []
 VrEye = []
@@ -1170,6 +1185,7 @@ WorkerOptions = []
 Worklet = []
 WorkletGlobalScope = []
 XPathExpression = []
+XPathNsResolver = []
 XPathResult = []
 XmlDocument = []
 XmlHttpRequest = []

crates/web-sys/webidls/enabled/EventTarget.webidl

@@ -29,12 +29,12 @@ interface EventTarget {
      false. */
   [Throws]
   void addEventListener(DOMString type,
-                        EventListener? listener,
+                        EventListener listener,
                         optional (AddEventListenerOptions or boolean) options,
                         optional boolean? wantsUntrusted = null);
   [Throws]
   void removeEventListener(DOMString type,
-                           EventListener? listener,
+                           EventListener listener,
                            optional (EventListenerOptions or boolean) options);
   [Throws, NeedsCallerType]
   boolean dispatchEvent(Event event);