src/vs/workbench/api/common/extHostWebviewView.ts/ExtHostWebviewViews/$onDidChangeWebviewViewVisibility
class ExtHostWebviewViews:	async $onDidChangeWebviewViewVisibility(
		webviewHandle: string,
		visible: boolean
	) {
		const webviewView = this.getWebviewView(webviewHandle);
		webviewView._setVisible(visible);
	}