Strange issue with Chrome 54.0.2840.71

[wmonk]

Chrome just updated today/yesterday to 54.0.2840.71. For some reason at various points of our component interactions, the main thread is blocked for ~5s. This is obviously painful to use, and from a bit of debugging I can see that webpack is trying to parse/fetch sourcemaps - although I'm not sure why.

I was able to change the webpack config to

- devtool: '#cheap-module-eval-source-map',
+ devtool: 'eval',

which has alleviated the problem. I have a feeling it's semi related to this issue http://github.com/devtool/issues/74, or the source mapper used in webpack.

[arunoda]

Yep. I we should try to do something about the devtool.

[arunoda]

Fixed with #577