Better Electron Support

[mattdesl]

Thanks to #79 this supports Electron already (an environment where we are both in a "browser" and in "node").

It might be good to do the same logic here, so that fs is used when possible rather than synchronous XHR (which is deprecated anyways):

node-source-map-support/source-map-support.js

Lines 63 to 76 in 70c54a8

	if (isInBrowser()) {
	var xhr = new XMLHttpRequest();
	xhr.open('GET', path, false);
	xhr.send(null);
	var contents = null
	if (xhr.readyState === 4 && xhr.status === 200) {
	contents = xhr.responseText
	}
	}
	// Otherwise, use the filesystem
	else {
	var contents = fs.readFileSync(path, 'utf8');
	}

[julien-f]

Good idea :)

PR are welcome :p

[niieani]

#140