Make Collapse/Expand All button of Search tree initialize correctly (fix microsoft#204316) (microsoft#205235)

Author: gjsjohnmurray

src/vs/workbench/contrib/search/browser/searchView.ts

@@ -901,6 +901,7 @@ export class SearchView extends ViewPane {
 		const updateHasSomeCollapsible = () => this.toggleCollapseStateDelayer.trigger(() => this.hasSomeCollapsibleResultKey.set(this.hasSomeCollapsible()));
 		updateHasSomeCollapsible();
 		this._register(this.tree.onDidChangeCollapseState(() => updateHasSomeCollapsible()));
+		this._register(this.tree.onDidChangeModel(() => updateHasSomeCollapsible()));
 
 		this._register(Event.debounce(this.tree.onDidOpen, (last, event) => event, DEBOUNCE_DELAY, true)(options => {
 			if (options.element instanceof Match) {