Add remove-diff-signs feature (#1866)

readme.md

@@ -155,6 +155,7 @@ GitHub Enterprise is also supported. More info in the options.
 - [Reaction comments ("+1", "👍", …) are hidden](https://user-images.githubusercontent.com/1402241/45543717-d45f3c00-b847-11e8-84a5-8c439d0ad1a5.png) (except the maintainers') [but they can still be shown.](https://user-images.githubusercontent.com/1402241/45543720-d628ff80-b847-11e8-9fb6-758a3102e3a9.png)
 - [Tall code blocks and quotes are limited in height.](https://github.com/sindresorhus/refined-github/issues/1123)
 - [Forks and watchers counters are hidden.](https://user-images.githubusercontent.com/1402241/53681077-f3328b80-3d1e-11e9-9e29-2cb017141769.png)
+- [Diff signs are hidden.](https://user-images.githubusercontent.com/1402241/54807718-149cec80-4cb9-11e9-869c-e265863211e3.png)
 
 ### UI improvements
 

source/content.css

@@ -228,6 +228,12 @@ followed someone
 	font-size: 13px;
 }
 
+/* For `remove-diff-signs` feature */
+.rgh-remove-diff-signs .blob-code-inner::before, /* Inline review blocks in PRs */
+.rgh-remove-diff-signs .blob-code-marker-cell::before { /* Commit page */
+	content: none;
+}
+
 /* For `fit-textareas` feature */
 .rgh-fit-textareas {
 	max-height: none !important;

source/content.ts

@@ -68,6 +68,7 @@ import './features/parse-backticks';
 import './features/swap-branches-on-compare';
 import './features/reactions-avatars';
 import './features/show-names';
+import './features/remove-diff-signs';
 import './features/view-markdown-source';
 import './features/mark-merge-commits-in-list';
 import './features/prev-next-commit-buttons';

source/features/remove-diff-signs.tsx

@@ -0,0 +1,10 @@
+import features from '../libs/features';
+
+function init() {
+	document.body.classList.add('rgh-remove-diff-signs');
+}
+
+features.add({
+	id: 'remove-diff-signs',
+	init
+});