Optimize Promise data structures. (#3768)

This patch reworks several structures:

- Fulfill and reject reactions are combined into one collection. The values in this collection
are compressed: a capability followed by an optional fulfill and reject functions.
- Fulfill and reject reactions are directly stored, no need to allocate an object for them.
- The job queue directly stores its items, this saves a pointer to the value, and the
callback is replaced by an uint8 type.
- Promise status and already resolved is stored in extra_info.

JerryScript-DCO-1.0-Signed-off-by: Zoltan Herczeg zherczeg.u-szeged@partner.samsung.com

jerry-core/lit/lit-magic-strings.h

@@ -34,14 +34,12 @@ typedef enum
   LIT_NON_INTERNAL_MAGIC_STRING__COUNT, /**< number of non-internal magic strings */
   LIT_INTERNAL_MAGIC_STRING_PROMISE = LIT_NON_INTERNAL_MAGIC_STRING__COUNT, /**<  [[Promise]] of promise
                                                                              *    reject or resolve functions */
-  LIT_INTERNAL_MAGIC_STRING_ALREADY_RESOLVED, /**< [[AlreadyResolved]] of promise reject or resolve functions */
   LIT_INTERNAL_MAGIC_STRING_RESOLVE_FUNCTION, /**< the resolve funtion of the promise object */
   LIT_INTERNAL_MAGIC_STRING_REJECT_FUNCTION, /**< the reject function of the promise object */
   LIT_INTERNAL_MAGIC_STRING_PROMISE_PROPERTY_PROMISE, /**< [[Promise]] property */
   LIT_INTERNAL_MAGIC_STRING_PROMISE_PROPERTY_RESOLVE, /**< [[Resolve]] property */
   LIT_INTERNAL_MAGIC_STRING_PROMISE_PROPERTY_REJECT, /**< [[Reject]] property */
   LIT_INTERNAL_MAGIC_STRING_PROMISE_PROPERTY_CAPABILITY, /**< [[Capability]] property */
-  LIT_INTERNAL_MAGIC_STRING_PROMISE_PROPERTY_HANDLER, /**< [[Handler]] property */
   LIT_INTERNAL_MAGIC_STRING_PROMISE_PROPERTY_ALREADY_CALLED, /**< [[AlreadyCalled]] property */
   LIT_INTERNAL_MAGIC_STRING_PROMISE_PROPERTY_INDEX, /**< [[Index]] property */
   LIT_INTERNAL_MAGIC_STRING_PROMISE_PROPERTY_VALUE, /**< [[Values]] property */