Create timezone transition data from the list of timezones in the "zones" variable. Depends on the installed ruby's Olson data being accurate.

timezones.rb

require 'rubygems'
require 'tzinfo'
require 'json'

# Run to generate Olson => goog.i18n.TimeZone data.

zones = %w(UTC Pacific/Auckland)

FIFTY_YEARS_FROM_NOW = DateTime.now + 365 * 50
MINUTES_IN_HOUR = 60
SECONDS_IN_HOUR = 60 * 60

def populate(zone, data)
  limit = FIFTY_YEARS_FROM_NOW
  names = data["names"] = []
  transitions = data["transitions"] = []
  d = 0
  while true
    period = zone.period_for_local(d)
    period_start = period.utc_start
    period_end = period.utc_end

    offset = (period.utc_total_offset - period.utc_offset) / MINUTES_IN_HOUR
    if names.empty? && offset == 0
      names << period.abbreviation.to_s
      names << period.abbreviation.to_s
    end

    if names.length == 2 && offset != 0
      names << period.abbreviation.to_s
      names << period.abbreviation.to_s
    end

    break if period_end.nil?
    transitions << period_start.strftime("%s").to_i / SECONDS_IN_HOUR
    transitions << offset
    if period_end > limit
      break
    else
      d = (period_end + 1).strftime("%s").to_i
    end
  end
end

puts zones.map {|z|
  zone = TZInfo::Timezone.get(z)
  output = {
    "id" => zone.name,
    "std_offset" => zone.period_for_utc(0).utc_offset / MINUTES_IN_HOUR
  }

  populate(zone, output)
  output
}.to_json