improve gfx and charting performance for text layout

[alex]

dojox.gfx._base includes a method called _getTextBox which is a significant performance problem. This code is replicated in the dojox.charting.axis2d.common API as the HTML variant of the createText method. Both of these methods make expensive calls to dojo.marginBox(). Charting axes should likely batch calls to find a maximum size wheras gfx should (at a minimum) use getBoundingClientRect where available. Getting actual border/margin boxes is likely less important in these cases than ensuring timely layout.

[liucougar]

(In [17597]) refs #9065: TextRectangle? object returned by getBoundingClientRect does not have width/height, it only has top/left/right/bottom this breaks underline shape in dojox.sketch

[Eugene Lazutkin]

This functionality was implemented by #9011 and refined in by #9357.