class Roadie::Inliner::StyleMap

it’s an accumulator for properties, scoped on specific elements.
StyleMap is a map between a DOM element and {StyleAttributeBuilder}. Basically,
@api private

def add(elements, new_properties) 

def add(elements, new_properties)
  Array(elements).each do |element|
    new_properties.each do |property|
      @map[element] << property
    end
  end
end

def each_element(&block) 

def each_element(&block)
  @map.each_pair(&block)
end

def initialize 

def initialize
  @map = Hash.new do |hash, key|
    hash[key] = StyleAttributeBuilder.new
  end
end