I18N of js files starting with c or d

This is one of many MRs opened in order to improve the overall
internationalisation of the GitLab codebase.

This commit only targets Vanilla JS files.

i18n documentation
https://docs.gitlab.com/ee/development/i18n/externalization.html

app/assets/javascripts/create_merge_request_dropdown.js

@@ -118,7 +118,7 @@ export default class CreateMergeRequestDropdown {
         this.branchCreated = true;
         window.location.href = data.url;
       })
-      .catch(() => Flash('Failed to create a branch for this issue. Please try again.'));
+      .catch(() => Flash(__('Failed to create a branch for this issue. Please try again.')));
   }
   createMergeRequest() {
@@ -130,7 +130,7 @@ export default class CreateMergeRequestDropdown {
         this.mergeRequestCreated = true;
         window.location.href = data.url;
       })
-      .catch(() => Flash('Failed to create Merge Request. Please try again.'));
+      .catch(() => Flash(__('Failed to create Merge Request. Please try again.')));
   }
   disable() {
@@ -227,7 +227,7 @@ export default class CreateMergeRequestDropdown {
       .catch(() => {
         this.unavailable();
         this.disable();
-        new Flash('Failed to get ref.');
+        new Flash(__('Failed to get ref.'));
         this.isGettingRef = false;

app/assets/javascripts/dropzone_input.js

@@ -4,6 +4,7 @@ import _ from 'underscore';
 import './behaviors/preview_markdown';
 import csrf from './lib/utils/csrf';
 import axios from './lib/utils/axios_utils';
+import { n__, __ } from '~/locale';
 Dropzone.autoDiscover = false;
@@ -90,7 +91,7 @@ export default function dropzoneInput(form) {
       if (!processingFileCount) $attachButton.removeClass('hide');
       addFileToForm(response.link.url);
     },
-    error: (file, errorMessage = 'Attaching the file failed.', xhr) => {
+    error: (file, errorMessage = __('Attaching the file failed.'), xhr) => {
       // If 'error' event is fired by dropzone, the second parameter is error message.
       // If the 'errorMessage' parameter is empty, the default error message is set.
       // If the 'error' event is fired by backend (xhr) error response, the third parameter is
@@ -273,19 +274,11 @@ export default function dropzoneInput(form) {
   };
   updateAttachingMessage = (files, messageContainer) => {
-    let attachingMessage;
     const filesCount = files.filter(file => file.status === 'uploading' || file.status === 'queued')
       .length;
-    // Dinamycally change uploading files text depending on files number in
-    // dropzone files queue.
-    if (filesCount > 1) {
-      attachingMessage = `Attaching ${filesCount} files -`;
-    } else {
-      attachingMessage = 'Attaching a file -';
-    }
-
-    messageContainer.text(attachingMessage);
+    const attachingMessage = n__('Attaching a file', 'Attaching %d files', filesCount);
+    messageContainer.text(`${attachingMessage} -`);
   };
   form.find('.markdown-selector').click(function onMarkdownClick(e) {

locale/gitlab.pot

@@ -1186,6 +1186,14 @@ msgstr ""
 msgid "Attach a file by drag & drop or %{upload_link}"
 msgstr ""
+msgid "Attaching a file"
+msgid_plural "Attaching %d files"
+msgstr[0] ""
+msgstr[1] ""
+
+msgid "Attaching the file failed."
+msgstr ""
+
 msgid "Aug"
 msgstr ""
@@ -4205,6 +4213,12 @@ msgstr ""
 msgid "Failed to connect to the prometheus server"
 msgstr ""
+msgid "Failed to create Merge Request. Please try again."
+msgstr ""
+
+msgid "Failed to create a branch for this issue. Please try again."
+msgstr ""
+
 msgid "Failed to create repository via gitlab-shell"
 msgstr ""
@@ -4214,6 +4228,9 @@ msgstr ""
 msgid "Failed to deploy to"
 msgstr ""
+msgid "Failed to get ref."
+msgstr ""
+
 msgid "Failed to install."
 msgstr ""