Bug 1470375 - Set the font editor pref to true in Nightly builds. r=gl

MozReview-Commit-ID: 1SKpRcD9VBZ

--HG--
extra : rebase_source : 630feea2217929ec345db943053f5b1909d98d22

devtools/client/preferences/devtools-client.js

@@ -65,8 +65,13 @@ pref("devtools.inspector.shapesHighlighter.enabled", true);
 pref("devtools.flexboxinspector.enabled", false);
 // Enable the new Animation Inspector
 pref("devtools.new-animationinspector.enabled", true);
-// Enable the Variable Fonts editor
+
+// Enable the Variable Fonts editor only in Nightly
+#if defined(NIGHTLY_BUILD)
+pref("devtools.inspector.fonteditor.enabled", true);
+#else
 pref("devtools.inspector.fonteditor.enabled", false);
+#endif
 // Enable the font highlight-on-hover feature
 pref("devtools.inspector.fonthighlighter.enabled", false);