src/vs/workbench/api/common/extHostWebviewView.ts/ExtHostWebviewViews/$disposeWebviewView
class ExtHostWebviewViews:	async $disposeWebviewView(webviewHandle: string) {
		const webviewView = this.getWebviewView(webviewHandle);
		this._webviewViews.delete(webviewHandle);
		webviewView.dispose();

		this._extHostWebview.deleteWebview(webviewHandle);
	}