add playbackrate as binding for mediaelements (#2202)

src/compile/nodes/Element.ts

@@ -534,7 +534,8 @@ export default class Element extends Node {
 				name === 'buffered' ||
 				name === 'seekable' ||
 				name === 'played' ||
-				name === 'volume'
+				name === 'volume' ||
+				name === 'playbackRate'
 			) {
 				if (this.name !== 'audio' && this.name !== 'video') {
 					component.error(binding, {

src/compile/render-dom/wrappers/Element/Attribute.ts

@@ -445,6 +445,7 @@ const attribute_lookup = {
 		],
 	},
 	volume: { applies_to: ['audio', 'video'] },
+	playbackRate: { applies_to: ['audio', 'video'] },
 	width: {
 		applies_to: ['canvas', 'embed', 'iframe', 'img', 'input', 'object', 'video'],
 	},

src/compile/render-dom/wrappers/Element/Binding.ts

@@ -139,6 +139,7 @@ export default class BindingWrapper {
 				break;
 
 			case 'currentTime':
+			case 'playbackRate':
 			case 'volume':
 				update_conditions.push(`!isNaN(${this.snippet})`);
 				break;

src/compile/render-dom/wrappers/Element/index.ts

@@ -83,7 +83,14 @@ const events = [
 		filter: (node: Element, name: string) =>
 			node.is_media_node() &&
 			name === 'volume'
-	}
+	},
+	{
+		event_names: ['ratechange'],
+		filter: (node: Element, name: string) =>
+			node.is_media_node() &&
+			name === 'playbackRate'
+	},
+
 ];
 
 export default class ElementWrapper extends Wrapper {