-- New JSObject for promises: JSPromise

Builtins
-- PromiseThen TFJ
-- PromiseCreateAndSet TFJ for internal use
-- PerformPromiseThen TFJ for internal use
-- PromiseInit for initial promise setup
-- SpeciesConstructor for use in PromiseThen
-- ThrowIfNotJSReceiver for use in SpeciesConstructor
-- AppendPromiseCallback to update FixedArray with new callback
-- InternalPerformPromiseThen

Promises.js
-- Cleanup unused symbols
-- Remove PerformPromiseThen
-- Remove PromiseThen
-- Remove PromiseSet
-- Remove PromiseAttachCallbacks

Runtime
-- PromiseSet to set promise inobject values
-- Refactor functions to use FixedArrays for callbacks instead of
   JSArray
-- Runtime_PromiseStatus to return promise status
-- Runtime_PromiseResult to return promise result
-- Runtime_PromiseDeferred to return deferred attached to promise
-- Runtime_PromiseRejectReactions to return reject reactions attached
   to promise

This CL results in a 13.07% improvement in the promises benchmark
(over 5 runs).

BUG=v8:5343

Review-Url: https://codereview.chromium.org/2536463002
Cr-Commit-Position: refs/heads/master@{#41503}