Explicitly convert raw data to strings

As strings are guaranteed to use UTF-8 in the GNOME platform, generic
file APIs like g_file_load_contents() return raw data instead. Since
gjs' recent update to mozjs60, this data is now returns as Uint8Array
which cannot simply be treated as string - its toString() method boils
down to arr.join(',') - so use gjs' new ByteArray module to explicitly
convert the data.

https://gitlab.gnome.org/GNOME/gnome-shell/merge_requests/179

js/misc/extensionUtils.js

@@ -112,6 +112,8 @@ function createExtensionObject(uuid, dir, type) {
     let metadataContents, success, tag;
     try {
         [success, metadataContents, tag] = metadataFile.load_contents(null);
+        if (metadataContents instanceof Uint8Array)
+            metadataContents = imports.byteArray.toString(metadataContents);
     } catch (e) {
         throw new Error('Failed to load metadata.json: ' + e);
     }

js/ui/keyboard.js

@@ -472,6 +472,8 @@ var KeyboardModel = new Lang.Class({
     _loadModel(groupName) {
         let file = Gio.File.new_for_uri('resource:///org/gnome/shell/osk-layouts/%s.json'.format(groupName));
         let [success, contents] = file.load_contents(null);
+        if (contents instanceof Uint8Array)
+            contents = imports.byteArray.toString(contents);
 
         return JSON.parse(contents);
     },

js/ui/padOsd.js

@@ -313,6 +313,8 @@ var PadDiagram = new Lang.Class({
     _init(params) {
         let file = Gio.File.new_for_uri('resource:///org/gnome/shell/theme/pad-osd.css');
         let [success, css, etag] = file.load_contents(null);
+        if (css instanceof Uint8Array)
+            css = imports.byteArray.toString(css);
         this._curEdited = null;
         this._prevEdited = null;
         this._css = css;

js/ui/sessionMode.js

@@ -117,6 +117,8 @@ function _loadMode(file, info) {
     let fileContent, success, tag, newMode;
     try {
         [success, fileContent, tag] = file.load_contents(null);
+        if (fileContent instanceof Uint8Array)
+            fileContent = imports.byteArray.toString(fileContent);
         newMode = JSON.parse(fileContent);
     } catch(e) {
         return;