update web-animations types based on PR review

Fixes microsoft/TypeScript#21492

Author: benbraou

baselines/dom.generated.d.ts

@@ -14854,14 +14854,15 @@ interface EventSourceInit {
 }
 
 interface AnimationOptions {
-    id?: DOMString;
+    id?: string;
     delay?: number;
     direction?: "normal" | "reverse" | "alternate" | "alternate-reverse";
     duration?: number;
     easing?: string;
     endDelay?: number;
     fill?: "none" | "forwards" | "backwards" | "both"| "auto";
     iterationStart?: number;
+    iterations?: number;
 }
 
 interface AnimationTimeline {
@@ -14881,6 +14882,21 @@ interface AnimationEffectReadOnly {
     getComputedTiming() => ComputedTimingProperties;
 }
 
+interface AnimationPlaybackEventInit extends EventInit {
+    currentTime?: number | null;
+    timelineTime?: number | null;
+}
+
+interface AnimationPlaybackEvent extends Event {
+    readonly currentTime: number | null;
+    readonly timelineTime: number | null;
+}
+
+declare var AnimationPlaybackEvent: {
+    prototype: AnimationPlaybackEvent;
+    new(type: string, eventInitDict?: AnimationPlaybackEventInit): AnimationPlaybackEvent;
+};
+
 interface Animation {
     currentTime: number | null;
     effect: AnimationEffectReadOnly;
@@ -14892,8 +14908,8 @@ interface Animation {
     readonly ready: Promise<Animation>;
     startTime: number;
     timeline: AnimationTimeline;
-    oncancel() => void;
-    oncancel() => void;
+    oncancel: (this: Animation, ev: AnimationPlaybackEvent) => any;
+    onfinish: (this: Animation, ev: AnimationPlaybackEvent) => any;
     cancel(): void;
     finish(): void;
     pause(): void;
@@ -15414,8 +15430,7 @@ type ScrollRestoration = "auto" | "manual";
 type FormDataEntryValue = string | File;
 type InsertPosition = "beforebegin" | "afterbegin" | "beforeend" | "afterend";
 type HeadersInit = Headers | string[][] | { [key: string]: string };
-type DOMString = string;
-type AnimationKeyFrame = {[key: string]: string | number | [string | number, string | number] | undefined};
+type AnimationKeyFrame = {offset?: number | null | (number | null)[]} & {[key: string]: string | number | number[] | string[]};
 type AppendMode = "segments" | "sequence";
 type AudioContextState = "suspended" | "running" | "closed";
 type BiquadFilterType = "lowpass" | "highpass" | "bandpass" | "lowshelf" | "highshelf" | "peaking" | "notch" | "allpass";

baselines/webworker.generated.d.ts

@@ -1917,7 +1917,6 @@ type IDBValidKey = number | string | Date | IDBArrayKey;
 type BufferSource = ArrayBuffer | ArrayBufferView;
 type FormDataEntryValue = string | File;
 type HeadersInit = Headers | string[][] | { [key: string]: string };
-type DOMString = string;
 type IDBCursorDirection = "next" | "nextunique" | "prev" | "prevunique";
 type IDBRequestReadyState = "pending" | "done";
 type IDBTransactionMode = "readonly" | "readwrite" | "versionchange";

inputfiles/addedTypes.json

@@ -2729,16 +2729,11 @@
         "name": "onvisibilitychange",
         "type": "(this: Document, ev: Event) => any"
     },
-    {
-        "kind": "typedef",
-        "name": "DOMString",
-        "type": "string"
-    },
     {
         "kind": "typedef",
         "flavor": "Web",
         "name": "AnimationKeyFrame",
-        "type": "{[key: string]: string | number | [string | number, string | number] | undefined}"
+        "type": "{offset?: number | null | (number | null)[]} & {[key: string]: string | number | number[] | string[]}"
     },       
     {
         "kind": "interface",
@@ -2747,7 +2742,7 @@
         "properties": [
             {
                 "name": "id?",
-                "type": "DOMString"
+                "type": "string"
             },
             {
                 "name": "delay?",
@@ -2776,7 +2771,11 @@
             {
                 "name": "iterationStart?",
                 "type": "number"
-            }           
+            },
+            {
+                "name": "iterations?",
+                "type": "number"
+            }
         ]
     },       
     {
@@ -2837,7 +2836,44 @@
                 ]
             }         
         ]        
-    },       
+    },
+    {
+        "kind": "interface",
+        "flavor": "Web",
+        "name": "AnimationPlaybackEventInit",
+        "extends": "EventInit",
+        "properties": [
+            {
+                "name": "currentTime?",
+                "type": "number | null"
+            },
+            {
+                "name": "timelineTime?",
+                "type": "number | null"
+            }
+        ]
+    },
+    {
+        "kind": "interface",
+        "flavor": "Web",
+        "name": "AnimationPlaybackEvent",
+        "extends": "Event",
+        "constructorSignatures": [
+            "new(type: string, eventInitDict?: AnimationPlaybackEventInit): AnimationPlaybackEvent"
+        ],        
+        "properties": [
+            {
+                "readonly": true,
+                "name": "currentTime",
+                "type": "number | null"
+            },
+            {
+                "readonly": true,
+                "name": "timelineTime",
+                "type": "number | null"
+            }
+        ]
+    },    
     {
         "kind": "interface",
         "flavor": "Web",
@@ -2895,13 +2931,13 @@
             {
                 "name": "oncancel",
                 "signatures": [
-                    "oncancel() => void"
+                    "oncancel: (this: Animation, ev: AnimationPlaybackEvent) => any"
                 ]
             },
             {
                 "name": "onfinish",
                 "signatures": [
-                    "oncancel() => void"
+                    "onfinish: (this: Animation, ev: AnimationPlaybackEvent) => any"
                 ]
             },
             {