I want to get rid of the separate libjavascriptcoregtk.so and install just a single libwebkitgtk.so so that we can stop exporting internal symbols from bmalloc, WTF, and JSC. This will probably also improve performance. For starters, we can implement this change as a non-default PRIVATE build option to facilitate testing. This option will likely be short-lived, because API stabilization is soon, and surely we'll only want to support one way or the other.