Finalize TreeItemLabel API

Fixes #61579

src/vs/vscode.d.ts

@@ -8727,7 +8727,7 @@ declare module 'vscode' {
 		/**
 		 * A human-readable string describing this item. When `falsy`, it is derived from [resourceUri](#TreeItem.resourceUri).
 		 */
-		label?: string;
+		label?: string | TreeItemLabel;
 
 		/**
 		 * Optional id for the tree item that has to be unique across tree. The id is used to preserve the selection and expansion state of the tree item.
@@ -8830,6 +8830,23 @@ declare module 'vscode' {
 		Expanded = 2
 	}
 
+	/**
+	 * Label describing the [Tree item](#TreeItem)
+	 */
+	export interface TreeItemLabel {
+
+		/**
+		 * A human-readable string describing the [Tree item](#TreeItem).
+		 */
+		label: string;
+
+		/**
+		 * Ranges in the label to highlight. A range is defined as a tuple of two number where the
+		 * first is the inclusive start index and the second the exclusive end index
+		 */
+		highlights?: [number, number][];
+	}
+
 	/**
 	 * Value-object describing what options a terminal should use.
 	 */

src/vs/vscode.proposed.d.ts

@@ -998,23 +998,6 @@ declare module 'vscode' {
 	//#endregion
 
 	//#region Tree View: https://github.com/microsoft/vscode/issues/61313
-	/**
-	 * Label describing the [Tree item](#TreeItem)
-	 */
-	export interface TreeItemLabel {
-
-		/**
-		 * A human-readable string describing the [Tree item](#TreeItem).
-		 */
-		label: string;
-
-		/**
-		 * Ranges in the label to highlight. A range is defined as a tuple of two number where the
-		 * first is the inclusive start index and the second the exclusive end index
-		 */
-		highlights?: [number, number][];
-
-	}
 
 	// https://github.com/microsoft/vscode/issues/100741
 	export interface TreeDataProvider<T> {
@@ -1022,11 +1005,6 @@ declare module 'vscode' {
 	}
 
 	export class TreeItem2 extends TreeItem {
-		/**
-		 * Label describing this item. When `falsy`, it is derived from [resourceUri](#TreeItem.resourceUri).
-		 */
-		label?: string | TreeItemLabel | /* for compilation */ any;
-
 		/**
 		 * Content to be shown when you hover over the tree item.
 		 */

src/vs/workbench/api/common/extHostTreeViews.ts

@@ -33,7 +33,6 @@ function toTreeItemLabel(label: any, extension: IExtensionDescription): ITreeIte
 	if (label
 		&& typeof label === 'object'
 		&& typeof label.label === 'string') {
-		checkProposedApiEnabled(extension);
 		let highlights: [number, number][] | undefined = undefined;
 		if (Array.isArray(label.highlights)) {
 			highlights = (<[number, number][]>label.highlights).filter((highlight => highlight.length === 2 && typeof highlight[0] === 'number' && typeof highlight[1] === 'number'));