fix type

Author: adiguba

packages/svelte/src/compiler/types/legacy-nodes.d.ts

@@ -187,7 +187,7 @@ export interface LegacyTransition extends BaseNode {
 	name: string;
 	/** The 'y' in `transition:x={y}` */
 	expression: null | Expression;
-	modifiers: Array<'local' | 'global'>;
+	modifiers: Array<'local' | 'global' | 'this'>;
 	/** True if this is a `transition:` or `in:` directive */
 	intro: boolean;
 	/** True if this is a `transition:` or `out:` directive */