Make symbol exporting work on Windows.
Export ui/views library.
Export symbols of WebView(ui/views/controls/webview).
Also include webview in the dependencies.
Add the CONTENT_IMPLEMENTATION definetion.

For targets that uses content module but is not part of it (for example
the webview target), we need to define CONTENT_IMPLEMENTATION to fix
linking errors.
web_dialogs is a dependency of webview, export its symbols.