function incrementOffsets( offsets, inc ) {
	var i;
	for ( i = 0; i < offsets.length; i++ ) {
		offsets[ i ] += inc[ i ];
	}
	return offsets;
}
Increments index offsets according to a list of increments.

## Notes

-   This function mutates the list of index offsets.

@private
@param {NonNegativeIntegerArray} offsets - list of index offsets
@param {NonNegativeIntegerArray} inc - list of increments
@returns {NonNegativeIntegerArray} updated offsets