0.8 ActiveModel::Serializer _fast_attributes - raise NameError without backtrace

[kml]

For this test I'm getting ~x2 improvement on JRuby.
NameError is used internally for flow controll. Backtrace is not needed, so I'm not raising it.
Links: https://github.com/jruby/jruby/wiki/BacktraceGeneration https://www.coffeepowered.net/2011/06/17/jruby-performance-exceptions-are-not-flow-control/

u is istance of User class from bench/perf.rb

serializers = []

10_000.times do
  serializers << Class.new(ActiveModel::Serializer) do
    attributes :id, :name
  end
end

Benchmark.bm do |x|
  x.report("serializable_hash") do
    serializers.each do |serializer|
      serializer.new(u).serializable_hash
    end
  end
end

without patch:

$ jruby -S rake bench
Resolving dependencies.....
       user     system      total        real
serializable_hash 10.300000   0.610000  10.910000 (  7.324000)

with:

$ jruby -S rake bench
Resolving dependencies.....
       user     system      total        real
serializable_hash  6.470000   0.480000   6.950000 (  3.249000)

[bf4]

The build for 0.8 should be fixed if you don't mind rebasing this and force pushing