fix(Shadow): offsetX, offsetY and blur supports float

[proYang]

No description provided.

[proYang]

Before:

new fabric.Shadow('#FF0000 2.1px 2px 2px')

// blur: 0
// color: "#FF0000 2.1px"
// offsetX: 2
// offsetY: 2

Now:

new fabric.Shadow('#FF0000 2.1px 2px 2px')

// blur: 2
// color: "#FF0000"
// offsetX: 2.1
// offsetY: 2

OffsetX, offsetY and blur in fabric.Shadow did not support decimals. It's supported now.

[asturur]

Seems good to me. Thanks for the tests.
Would you go one step forward and also add a line to the changelog.md?

Add the tag NEXT on top, where usually the version is, and then add a line looking at the other changes for the format.

[proYang]

Seems good to me. Thanks for the tests.
Would you go one step forward and also add a line to the changelog.md?

Add the tag NEXT on top, where usually the version is, and then add a line looking at the other changes for the format.

Done!