function normalizeReportLoc(descriptor) {
	if (descriptor.loc.start) {
		return descriptor.loc;
	}
	return { start: descriptor.loc, end: null };
}
Normalizes a MessageDescriptor to always have a `loc` with `start` and `end` properties
@param {MessageDescriptor} descriptor A descriptor for the report from a rule.
@returns {{start: Location, end: (Location|null)}} An updated location that infers the `start` and `end` properties
from the `node` of the original descriptor, or infers the `start` from the `loc` of the original descriptor.