fixed incorrect block comment highlighting

Closes #141 (closed)

frontend/src/store/modules/submission-notes.ts

@@ -63,7 +63,12 @@ const submissionGetter = mb.read(function submission (state, getters) {
     ? getters.submissionType.programmingLanguage
     : 'c'
   const highlighted = hljs.highlight(language, state.submission.text || '', true).value
+  
+  let commentFlag = false
   return highlighted.split('\n').reduce((acc: {[k: number]: string}, cur, index) => {
+    if (cur.includes("/*")) commentFlag = true
+    cur = commentFlag ? '<span class="hljs-comment">' + cur + '</span>' : cur
+    if (cur.includes("*/")) commentFlag = false // so that the ending line will also be greyed out
     acc[index + 1] = cur
     return acc
   }, {})