#2132 - Replace all uses of foo_callback with foo

ale_linters/javascript/eslint.vim

@@ -4,7 +4,7 @@
 call ale#linter#Define('javascript', {
 \   'name': 'eslint',
 \   'output_stream': 'both',
-\   'executable_callback': 'ale#handlers#eslint#GetExecutable',
-\   'command_callback': 'ale#handlers#eslint#GetCommand',
+\   'executable': function('ale#handlers#eslint#GetExecutable'),
+\   'command': function('ale#handlers#eslint#GetCommand'),
 \   'callback': 'ale#handlers#eslint#Handle',
 \})