Utilize ESLint’s endLine and endColumn

Consider the following code snippet:

    function fn () {
      let x = 1
      return x
      x = 3
    }

By utilizing ESLint’s `endLine` and `endColumn` properties, we highlight the whole fourth line (`x = 3`) since it is unreachable code.

lib/utils/linter.js

@@ -1,12 +1,18 @@
 const getRuleURI = require('eslint-rule-documentation')
 const generateRange = require('atom-linter').generateRange
 
-function getRange (textEditor, line, col, src, lineStart) {
+function getRange (textEditor, line, col, endLine, endCol, src, lineStart) {
   line = typeof line !== 'undefined' ? parseInt((line - 1) + lineStart, 10) : 0
   col = typeof col !== 'undefined' ? parseInt(col - 1, 10) : 0
+  endLine = typeof endLine !== 'undefined' ? parseInt((endLine - 1) + lineStart, 10) : null
+  endCol = typeof endCol !== 'undefined' ? parseInt(endCol - 1, 10) : null
   src = src || ''
   src = src.substring(0, col)
 
+  if (endLine && endCol) {
+    return [[line, col], [endLine, endCol]]
+  }
+
   return generateRange(textEditor, line, col)
 }
 
@@ -30,7 +36,15 @@ module.exports = function (err, output) {
       excerpt: msg.message,
       location: {
         file: self.filePath,
-        position: getRange(self.textEditor, msg.line, msg.column, msg.source, self.lineStart)
+        position: getRange(
+          self.textEditor,
+          msg.line,
+          msg.column,
+          msg.endLine,
+          msg.endColumn,
+          msg.source,
+          self.lineStart
+        )
       }
     }