dimensions code refactor

[asturur]

Fixes handling of strokewidth limit cases.

I did this to move the logic of calculating how big is an object and put under a function _getUntransformedDimensions() to reuse when necessary.

Lot of functions like:
translateToCenterPoint
translateToOriginPoint
getPointByOrigin

relies on a wrong calculation of the object unscaled dimensions, assuming that
width * scaleX + strokewidth * scaleX
is the solution for everything.

While this is not true for

• horizontal lines with big strokewidth,
• object with strokewidth bigger than width
• and it won't work in situation where the object inside has a complex transform

For example you can try to paste this code in the current kitchensink and try to resize the resulting object:

// clear canvas
canvas.clear();

// add red rectangle
canvas.add(new fabric.Line([100,100,100,200],{
      fill: 'red',
      stroke: 'red',
      strokeWidth: 500,
    }));

You will see that the object moves while you resize it.
This pr fixes that behaviour.

And make easier handle objects where there is a transformMatrix or a skew

closes #2187

[kangax]

I love this cleanup and simplification! One thing — untransformed sounds strange to my ear. I would prefer nontransformed or even better withoutTransform.

[kangax]

Actually, no, getNonTransformedDimensions and getTransformedDimensions would be best, I think.

[asturur]

Done.

i will make more changes in little steps.

[kangax]

This is not ready yet? More changes coming?

[asturur]

no no, different PRs with different cleaning ( setCoords is the next one )

[kangax]

+changelog