enable meta+enter shortcut to quick submit

app/assets/javascripts/issue_show/components/edit_actions.vue

 <script>
+  import updateMixin from '../mixins/update';
   import eventHub from '../event_hub';
 
   export default {
+    mixins: [updateMixin],
     props: {
       canDestroy: {
         type: Boolean,
@@ -23,10 +25,6 @@
       },
     },
     methods: {
-      updateIssuable() {
-        this.formState.updateLoading = true;
-        eventHub.$emit('update.issuable');
-      },
       closeForm() {
         eventHub.$emit('close.form');
       },

app/assets/javascripts/issue_show/components/fields/description.vue

 <script>
   /* global Flash */
+  import updateMixin from '../../mixins/update';
   import markdownField from '../../../vue_shared/components/markdown/field.vue';
 
   export default {
+    mixins: [updateMixin],
     props: {
       formState: {
         type: Object,
@@ -44,7 +46,8 @@
         v-model="formState.description"
         ref="textarea"
         slot="textarea"
-        placeholder="Write a comment or drag your files here...">
+        placeholder="Write a comment or drag your files here..."
+        @keydown.meta.enter="updateIssuable">
       </textarea>
     </markdown-field>
   </div>

app/assets/javascripts/issue_show/components/fields/title.vue

 <script>
+  import updateMixin from '../../mixins/update';
+
   export default {
+    mixins: [updateMixin],
     props: {
       formState: {
         type: Object,
@@ -22,6 +25,7 @@
       type="text"
       placeholder="Issue title"
       aria-label="Issue title"
-      v-model="formState.title" />
+      v-model="formState.title"
+      @keydown.meta.enter="updateIssuable" />
   </fieldset>
 </template>

app/assets/javascripts/issue_show/mixins/update.js

+import eventHub from '../event_hub';
+
+export default {
+  methods: {
+    updateIssuable() {
+      this.formState.updateLoading = true;
+      eventHub.$emit('update.issuable');
+    },
+  },
+};