Google maps search doesn't work when added to the DOM after map

[DavidHudlow]

Due to the brittle logic in the _setLocation method, if map is already set and a search is initialized with default null values for latitude/longitude, it throws an error.

See https://github.com/DavidHudlow/polymer-starter-kit/commit/76ec24c79bf3d5c1cf89e9b776f5192c92593c37 for reproduction.