Use .substring() instead of the deprecated .substr()

[InSyncWithFoo]

.substr() is deprecated. .substring() should be used instead. Conveniently, the differences between these two methods have already been handled by the conditional checks.

The following lines are affected:

json5/lib/stringify.js

Lines 50 to 57 in de344f0

	if (typeof space === 'number') {
	if (space > 0) {
	space = Math.min(10, Math.floor(space))
	gap = ' '.substr(0, space)
	}
	} else if (typeof space === 'string') {
	gap = space.substr(0, 10)
	}