Refactor the IL10n implementations to utilize async methods rather than manually returning Promises

This changes the methods signatures of `GenericL10n`, `MozL10n`, and `NullL10n`.

web/firefoxcom.js

@@ -145,21 +145,20 @@ class MozL10n {
     this.mozL10n = mozL10n;
   }
 
-  getLanguage() {
-    return Promise.resolve(this.mozL10n.getLanguage());
+  async getLanguage() {
+    return this.mozL10n.getLanguage();
   }
 
-  getDirection() {
-    return Promise.resolve(this.mozL10n.getDirection());
+  async getDirection() {
+    return this.mozL10n.getDirection();
   }
 
-  get(property, args, fallback) {
-    return Promise.resolve(this.mozL10n.get(property, args, fallback));
+  async get(property, args, fallback) {
+    return this.mozL10n.get(property, args, fallback);
   }
 
-  translate(element) {
+  async translate(element) {
     this.mozL10n.translate(element);
-    return Promise.resolve();
   }
 }
 

web/genericl10n.js

@@ -27,28 +27,24 @@ class GenericL10n {
     });
   }
 
-  getLanguage() {
-    return this._ready.then((l10n) => {
-      return l10n.getLanguage();
-    });
+  async getLanguage() {
+    const l10n = await this._ready;
+    return l10n.getLanguage();
   }
 
-  getDirection() {
-    return this._ready.then((l10n) => {
-      return l10n.getDirection();
-    });
+  async getDirection() {
+    const l10n = await this._ready;
+    return l10n.getDirection();
   }
 
-  get(property, args, fallback) {
-    return this._ready.then((l10n) => {
-      return l10n.get(property, args, fallback);
-    });
+  async get(property, args, fallback) {
+    const l10n = await this._ready;
+    return l10n.get(property, args, fallback);
   }
 
-  translate(element) {
-    return this._ready.then((l10n) => {
-      return l10n.translate(element);
-    });
+  async translate(element) {
+    const l10n = await this._ready;
+    return l10n.translate(element);
   }
 }
 

web/interfaces.js

@@ -163,12 +163,12 @@ class IL10n {
   /**
    * @returns {Promise<string>} - Resolves to the current locale.
    */
-  getLanguage() {}
+  async getLanguage() {}
 
   /**
    * @returns {Promise<string>} - Resolves to 'rtl' or 'ltr'.
    */
-  getDirection() {}
+  async getDirection() {}
 
   /**
    * Translates text identified by the key and adds/formats data using the args
@@ -179,12 +179,12 @@ class IL10n {
    * @param {string} fallback
    * @returns {Promise<string>}
    */
-  get(key, args, fallback) { }
+  async get(key, args, fallback) { }
 
   /**
    * Translates HTML element.
    * @param {HTMLElement} element
    * @returns {Promise<void>}
    */
-  translate(element) { }
+  async translate(element) { }
 }

web/ui_utils.js

@@ -56,21 +56,19 @@ function formatL10nValue(text, args) {
  * @implements {IL10n}
  */
 let NullL10n = {
-  getLanguage() {
-    return Promise.resolve('en-us');
+  async getLanguage() {
+    return 'en-us';
   },
 
-  getDirection() {
-    return Promise.resolve('ltr');
+  async getDirection() {
+    return 'ltr';
   },
 
-  get(property, args, fallback) {
-    return Promise.resolve(formatL10nValue(fallback, args));
+  async get(property, args, fallback) {
+    return formatL10nValue(fallback, args);
   },
 
-  translate(element) {
-    return Promise.resolve();
-  },
+  async translate(element) { },
 };
 
 /**