src/vs/workbench/api/browser/mainThreadWebviewPanels.ts/MainThreadWebviewPanels/addWebviewInput
class MainThreadWebviewPanels:	public addWebviewInput(handle: extHostProtocol.WebviewHandle, input: WebviewInput, options: { serializeBuffersForPostMessage: boolean }): void {
		this._webviewInputs.add(handle, input);
		this._mainThreadWebviews.addWebview(handle, input.webview, options);

		input.webview.onDidDispose(() => {
			this._proxy.$onDidDisposeWebviewPanel(handle).finally(() => {
				this._webviewInputs.delete(handle);
			});
		});
	}