webpack and JS5 strict-mode causes Error on delete of local variable in cursor plugin

[jmaino]

When bundling in webpack - strict-mode is enabled.
This causes an error to occur during compilation due to attempts to delete local variables (which is not permitted in strict-mode).

This occurs on the following 2 lines of the jqplot.cursor.js plugin in the CursorLegendRenderer.prototype.draw function:

        delete series;
        delete s;

I'm w/a'ing by simply commenting out these 2 delete lines