add char.escape scope to escape sequences in single quoted strings

Author: guuido

src/languages/yaml.js

@@ -46,15 +46,12 @@ export default function(hljs) {
   const SINGLE_QUOTE_STRING = {
     className: 'string',
     relevance: 0,
-    variants: [
-      {
-        begin: /'/,
-        end: /'/
-      }
-    ],
+    begin: /'/,
+    end: /'/,
     contains: [
       {
-        begin: /''/,
+        match: /''/,
+        scope: 'char.escape',
         relevance: 0
       }
     ]

test/markup/yaml/string.expect.txt

@@ -10,4 +10,6 @@
 <span class="hljs-attr">key:</span> <span class="hljs-string">&quot;\\&quot;</span>
 <span class="hljs-attr">key:</span> <span class="hljs-string">&quot;\&quot;
 key: value&quot;</span>
-<span class="hljs-attr">key:</span> <span class="hljs-string">value</span>
+<span class="hljs-attr">key:</span> <span class="hljs-string">value</span>
+<span class="hljs-attr">key:</span> <span class="hljs-string">&#x27;<span class="hljs-char escape_">&#x27;&#x27;</span>&#x27;</span>
+<span class="hljs-attr">key:</span> <span class="hljs-string">&#x27;some<span class="hljs-char escape_">&#x27;&#x27;</span>value&#x27;</span>

test/markup/yaml/string.txt

@@ -11,4 +11,5 @@ key: "\\"
 key: "\"
 key: value"
 key: value
-
+key: ''''
+key: 'some''value'