Firefox Developer Edition (or any edition), separate Unity launcher icon (Ubuntu 14.04)

firefox-developer-edition.desktop

[Desktop Entry]
Encoding=UTF-8
Version=1.0
Type=Application
Name=Firefox Developer Edition
Icon=/opt/firefox/browser/icons/mozicon128.png
Path=/opt/firefox/firefox
Exec=/opt/firefox/firefox --class="firefox-developer" -P dev-edition-default %u
StartupNotify=true
StartupWMClass=firefox-developer
X-UnityGenerated=false
Actions=NewWindow;NewPrivateWindow;
Categories=GNOME;GTK;Network;WebBrowser;
Terminal=false
MimeType=text/html;text/xml;application/xhtml+xml;application/xml;application/rss+xml;application/rdf+xml;image/gif;image/jpeg;image/png;x-scheme-handler/http;x-scheme-handler/https;x-scheme-handler/ftp;x-scheme-handler/chrome;video/webm;application/x-xpinstall;

[Desktop Action NewWindow]
Name=Open a New Window
Path=/opt/firefox/firefox
Exec=/opt/firefox/firefox -new-window --class="firefox-developer" -P dev-edition-default
OnlyShowIn=Unity;

[Desktop Action NewPrivateWindow]
Name=Open a New Private Window
Path=/opt/firefox/firefox
Exec=/opt/firefox/firefox -private-window --class="firefox-developer"
OnlyShowIn=Unity;

# Change paths to match your username and location of firefox edition
# TODO: fix icon size :)
# To see shortcut in dash, relogin

See https://help.ubuntu.com/community/UnityLaunchersAndDesktopFiles for info on where to save the .desktop file.