test: make `toimage_test.js` stricter
test: make `toimage_test.js` stricter

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