rename titleOffset -> Axes.getPxPosition
rename titleOffset -> Axes.getPxPosition

... which is a more appropriate name.
    Moreover, improve its perf by using
    _anchorAxis cache instead of `getFromId`

etpinard/plotly.js,plotly/plotly.js,aburato/plotly.js,plotly/plotly.js,aburato/plotly.js,plotly/plotly.js,plotly/plotly.js,etpinard/plotly.js,etpinard/plotly.js