fixed eslint error & integrated with prettier as well as formatted the whole codebase (#3450)

browser/lib/Mutable.js

@@ -1,43 +1,43 @@
 class MutableMap {
-  constructor (iterable) {
+  constructor(iterable) {
     this._map = new Map(iterable)
     Object.defineProperty(this, 'size', {
       get: () => this._map.size,
-      set: function (value) {
+      set: function(value) {
         this['size'] = value
       }
     })
   }
 
-  get (...args) {
+  get(...args) {
     return this._map.get(...args)
   }
 
-  set (...args) {
+  set(...args) {
     return this._map.set(...args)
   }
 
-  delete (...args) {
+  delete(...args) {
     return this._map.delete(...args)
   }
 
-  has (...args) {
+  has(...args) {
     return this._map.has(...args)
   }
 
-  clear (...args) {
+  clear(...args) {
     return this._map.clear(...args)
   }
 
-  forEach (...args) {
+  forEach(...args) {
     return this._map.forEach(...args)
   }
 
-  [Symbol.iterator] () {
+  [Symbol.iterator]() {
     return this._map[Symbol.iterator]()
   }
 
-  map (cb) {
+  map(cb) {
     const result = []
     for (const [key, value] of this._map) {
       result.push(cb(value, key))
@@ -45,7 +45,7 @@ class MutableMap {
     return result
   }
 
-  toJS () {
+  toJS() {
     const result = {}
     for (let [key, value] of this._map) {
       if (value instanceof MutableSet || value instanceof MutableMap) {
@@ -58,42 +58,42 @@ class MutableMap {
 }
 
 class MutableSet {
-  constructor (iterable) {
+  constructor(iterable) {
     this._set = new Set(iterable)
     Object.defineProperty(this, 'size', {
       get: () => this._set.size,
-      set: function (value) {
+      set: function(value) {
         this['size'] = value
       }
     })
   }
 
-  add (...args) {
+  add(...args) {
     return this._set.add(...args)
   }
 
-  delete (...args) {
+  delete(...args) {
     return this._set.delete(...args)
   }
 
-  forEach (...args) {
+  forEach(...args) {
     return this._set.forEach(...args)
   }
 
-  [Symbol.iterator] () {
+  [Symbol.iterator]() {
     return this._set[Symbol.iterator]()
   }
 
-  map (cb) {
+  map(cb) {
     const result = []
-    this._set.forEach(function (value, key) {
+    this._set.forEach(function(value, key) {
       result.push(cb(value, key))
     })
 
     return result
   }
 
-  toJS () {
+  toJS() {
     return Array.from(this._set)
   }
 }