Closure Compiler Error with ES6 code and Dojo 1.16.0?

https://discourse.dojo.io/t/closure-compiler-strict-errors/456

As reported by yassam:

I’m using Dojo 1.16.0.

The Dojo build system is giving me INTERNAL COMPILER ERROR on my ES6 code. I figure this might be due to a buggy version of the Closure compiler shipped with Dojo, so I downloaded the latest version of the Closure compiler and I now get a bunch of errors in the dojo code itself.

It complains about dojo code not compiling in strict mode, even though I haven’t set strict mode.

Specifically, here’s the relevant part of my build profile:

layerOptimize: 'closure',
optimize: 'closure',

optimizeOptions: {
languageIn: 'ECMASCRIPT6',
languageOut: 'ECMASCRIPT5'
},

Note that the input language is ECMASCRIPT6 not ECMASCRIPT6_STRICT

Is there an easy way to get the latest version of the closure compiler to work?