fix: add Mocha to global variable

[irrationnelle]

Requirements

• Filling out the template is required. Any pull request that does not include enough information to be reviewed in a timely manner may be closed at the maintainers' discretion.
• All new code requires tests to ensure against regressions.

Description of the Change

To apply UMD pattern, Mocha module was located in mocha as module name. But browsers are be able to access Mocha as global variable with this change.

I added rollup config footer to assign Mocha module to global variable. I hope that this would be the alias to acutal Mocha module, not deep cloning another Mocha.

Alternate Designs

in browser-entry.js from line 213

mocha.Mocha = Mocha;
mocha.mocha = mocha;

I would like to suggest like next

global.Mocha = Mocha;
global.mocha = mocha;

OR,

mocha.Mocha = Mocha;
mocha.mocha = mocha;

(function(currentGlobal) {
  currentGlobal.Mocha = mocha.Mocha;
})(global);

anyway, I was afraid of any side-effects and then I selected this version as PR.

Benefits

• Users who used mocha for browsers could update the latest mocha
• Other third party modules with global variable Mocha could update the latest mocha

Possible Drawbacks

There would be duplicated Mocha modules on browser.
IMHO, an alias for this module would be better than assign object but I would like to avoid to modify core code.

Applicable issues

#4395

Versioning Info

• Is this a breaking change (major release)? No
• Is it an enhancement (minor release)? No
• Is it a bug fix, or does it not impact production code (patch release)? Yes

[jsf-clabot]

All committers have signed the CLA.

[coveralls]

Coverage increased (+0.06%) to 93.849% when pulling 814338e on irrationnelle:fix/global-variable-for-Mocha into 78d979d on mochajs:master.

[boneskull]

LGTM, thanks

[boneskull]

maybe putting this in browser-entry.js would be better, but we can change it later.