Allow Chrome-compatible ES6 syntax to pass linter

Some valid ES6 & Chrome compatible syntax won't make it through the minifier's linter. For projects targeting only the latest version of Chrome, it'd be nice for ES6 syntax to be able to build.

Creating this issue to catalog valid/non-working syntax:

- template strings
- arrow functions
- trailing commas in function arguments lists

Start by examining the minifier's linter and how it parses or validates JavaScript syntax. Use the listed template strings, arrow functions, and trailing commas in function argument lists as cases to check. Done means valid ES6 syntax compatible with current Chrome can pass the linter and build.

Written by the indexing model from the issue text.