🐛 Treat empty comment line as comment and add tests (Fix #4140)

src/language-mode.coffee

@@ -147,13 +147,11 @@ class LanguageMode
 
     if bufferRow > 0
       for currentRow in [bufferRow-1..0] by -1
-        break if @buffer.isRowBlank(currentRow)
         break unless @editor.displayBuffer.tokenizedBuffer.tokenizedLineForRow(currentRow).isComment()
         startRow = currentRow
 
     if bufferRow < @buffer.getLastRow()
       for currentRow in [bufferRow+1..@buffer.getLastRow()] by 1
-        break if @buffer.isRowBlank(currentRow)
         break unless @editor.displayBuffer.tokenizedBuffer.tokenizedLineForRow(currentRow).isComment()
         endRow = currentRow
 

src/tokenized-line.coffee

@@ -498,7 +498,6 @@ class TokenizedLine
     while iterator.next()
       scopes = iterator.getScopes()
       continue if scopes.length is 1
-      continue unless NonWhitespaceRegex.test(iterator.getText())
       for scope in scopes
         if CommentScopeRegex.test(scope)
           @isCommentLine = true