Enable resource decorations for some tree tooltips (microsoft#158593)

Part of microsoft/vscode-pull-request-github#3644

Author: alexr00

src/vs/workbench/browser/labels.ts

@@ -587,8 +587,13 @@ class ResourceLabelWidget extends IconLabel {
 
 			const decoration = this.decoration.value;
 			if (decoration) {
-				if (decoration.tooltip && (typeof iconLabelOptions.title === 'string')) {
-					iconLabelOptions.title = `${iconLabelOptions.title} • ${decoration.tooltip}`;
+				if (decoration.tooltip) {
+					if (typeof iconLabelOptions.title === 'string') {
+						iconLabelOptions.title = `${iconLabelOptions.title} • ${decoration.tooltip}`;
+					} else if (typeof iconLabelOptions.title?.markdown === 'string') {
+						const title = `${iconLabelOptions.title.markdown} • ${decoration.tooltip}`;
+						iconLabelOptions.title = { markdown: title, markdownNotSupportedFallback: title };
+					}
 				}
 
 				if (decoration.strikethrough) {

src/vs/workbench/browser/parts/views/treeView.ts

@@ -1010,11 +1010,12 @@ class TreeRenderer extends Disposable implements ITreeRenderer<ITreeItem, FuzzyS
 		}
 
 		return {
-			markdown: (token: CancellationToken): Promise<IMarkdownString | string | undefined> => {
-				return new Promise<IMarkdownString | string | undefined>((resolve) => {
-					node.resolve(token).then(() => resolve(node.tooltip));
-				});
-			},
+			markdown: typeof node.tooltip === 'string' ? node.tooltip :
+				(token: CancellationToken): Promise<IMarkdownString | string | undefined> => {
+					return new Promise<IMarkdownString | string | undefined>((resolve) => {
+						node.resolve(token).then(() => resolve(node.tooltip));
+					});
+				},
 			markdownNotSupportedFallback: resource ? undefined : (label ?? '') // Passing undefined as the fallback for a resource falls back to the old native hover
 		};
 	}