As Swiss voters head to the polls tomorrow, the country is weighing a proposal that could redraw its economic future and strain its ties with the European Union — a high-stakes referendum some have compared to Britain's Brexit vote. What does the proposal envisage? Under the plan, Switzerland's population, now at 9.1 million, would be barred from rising above 10 million before 2050. Current projections do not expect that threshold to be reached until the early 2040s. If the population climbs to 9.5 million, the government…