Don't show open/save dialog in addition to style installation prompt
Don't show open/save dialog in addition to style installation prompt

This apparently has been happening for a year, since #617.

Might be better to show open/save on cancel, as implemented for the
RIS/BibTeX prompt in 4ecdd55 (which caused this), but that would have to
wait for the better promise handling in 5.0. Doing "Save Link As..." for
a CSL file also seems a bit more straightforward than for RIS/BibTeX,
which can be served in complicated ways.

rmzelle/zotero,LinuxMercedes/zotero,gracile-fr/zotero,sendecomp/zotero,retorquere/zotero,sendecomp/zotero,LinuxMercedes/zotero,retorquere/zotero,sendecomp/zotero,LinuxMercedes/zotero,retorquere/zotero,gracile-fr/zotero,rmzelle/zotero,gracile-fr/zotero,rmzelle/zotero