impl ppb_url_util_dev_resolve_relative_to_document
make use of PP_MakeString/PP_MakeStringN
construct full url from relative in ppb_url_loader_open
fix crash with already removed url loader
fix return value in ppb_url_loader_open()
call callback in NPP_DestroyStream
mark ppb_url_loader_open as partially implemented
impl stub for ppb_browser_font_trusted
impl stub for ppb_audio