Add browserShadowBlurConstant to adjust shadowBlur value

[melvynhills]

Expose browserShadowBlurConstant to adjust shadowBlur value
close #4402

[asturur]

would you mind check if there are some tests of setShadow in the object tests and in case add one that demostrate that this thing works?

i can guide you.

[melvynhills]

Yeah in fact I tried to run the tests by following the Readme but when running testem I had errors of QUnit missing, although I did npm install and even npm install qunit -g 😕

[asturur]

use npm run test testem is a change that got unfinished.

[melvynhills]

I get this error when running npm run test :

[asturur]

remove that npm install quint -g that you did before and reinstall fabric?

[melvynhills]

What do you mean by "reinstall fabric" ?
What I did:

• npm uninstall qunit -g
• rm -rf node_modules
• npm install
• npm run build
• npm run test

=> Still have the same error.

(I see you opened a PR specifically for this, I guess it should ring a bell?)

Then I just tried to patch QUnit with QUnit.ok = QUnit.assert.ok.bind(QUnit.assert);, that kinda worked but then I get another error (maybe the one caught by QUnit in the first place) :

{ Error: Image given has not completed loading
    at /fabric.js/test/unit/image.js:68:35
    at /fabric.js/test/unit/image.js:99:21
    at FSReqWrap.readFileAfterClose [as oncomplete] (fs.js:513:3) message: 'Image given has not completed loading' }

Note: I'm using Node v8.8.0

[melvynhills]

Skipped all tests but unit/object.js so I could run the suite, because I have errors with any test involving fabric.Image.

Added a simple test, tell me if it's enough. Thanks

[asturur]

If you have trouble running image tests it does me bring to think you have problem installing node-canvas.

[asturur]

test is ok, i just added descriptions so that if it fails you know what failed. if i did not broke linting i m going merge right now.