Update the eslint-plugin-mozilla package to the latest version

With the updated compatibility for the addon, we can thus remove a few no longer needed exceptions from `extensions/firefox/.eslintrc`.

extensions/firefox/.eslintrc

@@ -7,17 +7,6 @@
   ],
 
   "parserOptions": {
-    // Note: Remove the ecmaVersion line when Gecko 52 is no longer supported
-    // to pick up the eslint-plugin-mozilla version (or at least update to
-    // ecmaVersion 8).
-    "ecmaVersion": 6,
-    "ecmaFeatures": {
-      // Note: We turn this off as it was only added in Gecko 55 (Bug 1339395)
-      // and we still need to support older versions (eslint-plugin-mozilla turns
-      // it on).
-      "experimentalObjectRestSpread": false
-    },
-
     "sourceType": "script",
   },
 
@@ -28,9 +17,6 @@
   "rules": {
     // Items different from the mozilla/recommended configuration.
 
-    // Being enabled soon.
-    "mozilla/use-services": "error",
-
     // Other rules mozilla/recommended hasn't enabled yet.
     "no-shadow": "error",
     "arrow-body-style": ["error", "as-needed"],

extensions/firefox/content/PdfJsNetwork.jsm

@@ -19,7 +19,7 @@ ChromeUtils.import("resource://gre/modules/Services.jsm");
 
 var EXPORTED_SYMBOLS = ["NetworkManager"];
 
-function log(aMsg) {
+function log(aMsg) { // eslint-disable-line no-unused-vars
   var msg = "PdfJsNetwork.jsm: " + (aMsg.join ? aMsg.join("") : aMsg);
   Services.console.logStringMessage(msg);
 }

extensions/firefox/content/PdfStreamConverter.jsm

@@ -23,7 +23,6 @@ const Cr = Components.results;
 const Cu = Components.utils;
 
 const PDFJS_EVENT_ID = "pdf.js.message";
-const PDF_CONTENT_TYPE = "application/pdf";
 const PREF_PREFIX = "PDFJSSCRIPT_PREF_PREFIX";
 const PDF_VIEWER_WEB_PAGE = "resource://pdf.js/web/viewer.html";
 const MAX_NUMBER_OF_PREFS = 50;

package.json

@@ -10,7 +10,7 @@
     "core-js": "^2.5.3",
     "escodegen": "^1.9.0",
     "eslint": "^4.16.0",
-    "eslint-plugin-mozilla": "^0.5.0",
+    "eslint-plugin-mozilla": "^0.7.0",
     "eslint-plugin-no-unsanitized": "^2.0.2",
     "fancy-log": "^1.3.2",
     "gulp": "^3.9.1",