wry@0.39.4

8bbc2bf(#1237) Fix WebviewBuilder::with_transparent, WebviewBuilder::with_background_color, and Webview::set_background_color always failing and causing the webview to fail to load.
130c469(#1238) Add WebViewBuilderExtDarwin::with_data_store_identifier.
203604c(#1233) On Windows, fix the webview not filling up the whole window if the parent window was resized during the webview initialization.