UserAgent: Mozilla/5.0 (Windows NT 6.3; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/65.0.3325.146 Safari/537.36

Steps to reproduce the problem:
1. Define about 15 es6 mixins (few of them are depend on the others)
2. Create custom-element class extending Polymer.Element with these mixins 

What is the expected behavior?

What went wrong?
Browser crashes

Crashed report ID: b06c7c15-30eb-4e67-a5a3-b49aa8db8d97

How much crashed? Just one tab

Is it a problem with a plugin? No 

Did this work before? Yes 

Chrome version: 65.0.3325.146  Channel: stable
OS Version: 6.3
Flash Version: