Firefox Developer Edition includes latest Developer Tools

Step 1. Download Firefox Quantum: Developer Edition

Download Firefox Developer Edition.

Step 2. Extract files

Extract tar.bz2 file:

tar -xvjf firefox-X.X.tar.bz2

Step 3. Move firefox to suitable location

Move the extracted firefox folder to /opt/firefox-dev directory:

sudo mv firefox /opt/firefox-dev

Step 4. Add .desktop file

Created a .desktop file .local/share/applications/firefox-developer.desktop with the contents below:

[Desktop Entry]
Version=1.0
Name=Firefox Developer Edition
Comment=Firefox Aurora with Developer tools
GenericName=Web Browser
Keywords=Internet;WWW;Browser;Web;Explorer
Exec=/opt/firefox-dev/firefox %u
Terminal=false
X-MultipleArgs=false
Type=Application
Icon=/opt/firefox-dev/browser/chrome/icons/default/default128.png
Categories=GNOME;GTK;Network;WebBrowser;
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;
StartupNotify=true
Actions=new-window;new-private-window;

[Desktop Action new-window]
Name=Open a New Window
Name[ar]=افتح نافذة جديدة
Name[ast]=Abrir una ventana nueva
Name[bn]=Abrir una ventana nueva
Name[ca]=Obre una finestra nova
Name[cs]=Otevřít nové okno
Name[da]=Åbn et nyt vindue
Name[de]=Ein neues Fenster öffnen
Name[el]=Άνοιγμα νέου παραθύρου
Name[es]=Abrir una ventana nueva
Name[fi]=Avaa uusi ikkuna
Name[fr]=Ouvrir une nouvelle fenêtre
Name[gl]=Abrir unha nova xanela
Name[he]=פתיחת חלון חדש
Name[hr]=Otvori novi prozor
Name[hu]=Új ablak nyitása
Name[it]=Apri una nuova finestra
Name[ja]=新しいウィンドウを開く
Name[ko]=새 창 열기
Name[ku]=Paceyeke nû veke
Name[lt]=Atverti naują langą
Name[nb]=Åpne et nytt vindu
Name[nl]=Nieuw venster openen
Name[pt]=Abrir nova janela
Name[pt_BR]=Abrir nova janela
Name[ro]=Deschide o fereastră nouă
Name[ru]=Новое окно
Name[sk]=Otvoriť nové okno
Name[sl]=Odpri novo okno
Name[sv]=Öppna ett nytt fönster
Name[tr]=Yeni pencere aç 
Name[ug]=يېڭى كۆزنەك ئېچىش
Name[uk]=Відкрити нове вікно
Name[vi]=Mở cửa sổ mới
Name[zh_CN]=新建窗口
Name[zh_TW]=開啟新視窗
Exec=/opt/firefox-dev/firefox -new-window

[Desktop Action new-private-window]
Name=Open a New Private Window
Name[ar]=افتح نافذة جديدة للتصفح الخاص
Name[ca]=Obre una finestra nova en mode d'incògnit
Name[de]=Ein neues privates Fenster öffnen
Name[es]=Abrir una ventana privada nueva
Name[fi]=Avaa uusi yksityinen ikkuna
Name[fr]=Ouvrir une nouvelle fenêtre de navigation privée
Name[he]=פתיחת חלון גלישה פרטית חדש
Name[hu]=Új privát ablak nyitása
Name[it]=Apri una nuova finestra anonima
Name[nb]=Åpne et nytt privat vindu
Name[ru]=Новое приватное окно
Name[sl]=Odpri novo okno zasebnega brskanja
Name[tr]=Yeni bir pencere aç
Name[uk]=Відкрити нове вікно у потайливому режимі
Name[zh_TW]=開啟新隱私瀏覽視窗
Exec=/opt/firefox-dev/firefox -private-window

Firefox Developer Edition should now appear in the Applications dock.