Handle case where cssRules are undefined.
Handle case where cssRules are undefined.

It's possible for a stylesheet's cssRules property to be undefined. In
that case, break out of the rule aggregating loop.

Don't explicitly refer to module.exports.

plotly/plotly.js,asolagmbh/plotly.js,plotly/plotly.js,iongroup/plotly.js,iongroup/plotly.js,aburato/plotly.js,asolagmbh/plotly.js,iongroup/plotly.js,asolagmbh/plotly.js,etpinard/plotly.js,plotly/plotly.js,etpinard/plotly.js,plotly/plotly.js,aburato/plotly.js,etpinard/plotly.js