Upgrade eslint to v5

We needed to disable a few eslint-config-airbnb-base rules in order
to keep the number of line changes under control.  These should be
re-enabled asap.

.eslintrc.yml

@@ -56,6 +56,10 @@ rules:
         component: always
       svg: always
       math: always
+  camelcase:
+    - error
+    - properties: never
+      ignoreDestructuring: true
   ## Conflicting rules with prettier:
   space-before-function-paren: off
   curly: off
@@ -63,7 +67,7 @@ rules:
   function-paren-newline: off
   object-curly-newline: off
   padded-blocks: off
-  # Disabled for now, to make the eslint 3 -> eslint 4 update smoother
+  # Disabled for now, to make the eslint 3 -> eslint 5 update smoother
   ## Indent rule. We are using the old for now: https://eslint.org/docs/user-guide/migrating-to-4.0.0#indent-rewrite
   indent: off
   indent-legacy:
@@ -78,3 +82,11 @@ rules:
       FunctionExpression:
         parameters: 1
         body: 1
+  # Disabled for now, to make the airbnb-base 12.1.0 -> 13.1.0 update smoother
+  operator-linebreak: off
+  implicit-arrow-linebreak: off
+  no-else-return:
+    - error
+    - allowElseIf: true
+  import/no-useless-path-segments: off
+  lines-between-class-members: off

app/assets/javascripts/boards/index.js

@@ -9,7 +9,7 @@ import '~/vue_shared/models/assignee';
 
 import FilteredSearchBoards from './filtered_search_boards';
 import eventHub from './eventhub';
-import sidebarEventHub from '~/sidebar/event_hub'; // eslint-disable-line import/first
+import sidebarEventHub from '~/sidebar/event_hub';
 import './models/issue';
 import './models/list';
 import './models/milestone';
@@ -24,7 +24,7 @@ import './components/board';
 import './components/board_sidebar';
 import './components/new_list_dropdown';
 import BoardAddIssuesModal from './components/modal/index.vue';
-import '~/vue_shared/vue_resource_interceptor'; // eslint-disable-line import/first
+import '~/vue_shared/vue_resource_interceptor';
 
 export default () => {
   const $boardApp = document.getElementById('board-app');

app/assets/javascripts/merge_request_tabs.js

@@ -115,8 +115,9 @@ export default class MergeRequestTabs {
       this.mergeRequestTabs &&
       this.mergeRequestTabs.querySelector(`a[data-action='${action}']`) &&
       this.mergeRequestTabs.querySelector(`a[data-action='${action}']`).click
-    )
+    ) {
       this.mergeRequestTabs.querySelector(`a[data-action='${action}']`).click();
+    }
     this.initAffix();
   }
 

package.json

@@ -117,12 +117,12 @@
     "babel-types": "^6.26.0",
     "chalk": "^2.4.1",
     "commander": "^2.15.1",
-    "eslint": "~4.12.1",
-    "eslint-config-airbnb-base": "^12.1.0",
+    "eslint": "~5.6.0",
+    "eslint-config-airbnb-base": "^13.1.0",
     "eslint-import-resolver-webpack": "^0.10.0",
     "eslint-plugin-filenames": "^1.2.0",
     "eslint-plugin-html": "4.0.3",
-    "eslint-plugin-import": "^2.12.0",
+    "eslint-plugin-import": "^2.14.0",
     "eslint-plugin-jasmine": "^2.1.0",
     "eslint-plugin-promise": "^3.8.0",
     "eslint-plugin-vue": "^4.5.0",