Support custom size policy for graph

[#44384929]
Fix a bug in RealTimeGrapher causing its weird scaling

[#44384929]

"if (!arguments.length)" wasn't the best idea here. This scale(w, h)
function was called from resize(w, h) function, where w, h were always
present, but sometimes undefined. So, two 'undefined' were passed and
scale logic was misled (as two undefined passed caused that
arguments.length == 2).