Implement yield* operator (#3923)

Missing features:
- caching next() method (this also true for normal generators)
- automatic sync to async generator conversion

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

jerry-core/vm/vm-defines.h

@@ -71,6 +71,12 @@ typedef struct vm_frame_ctx_t
  */
 #define VM_GET_REGISTER(frame_ctx_p, i) (((ecma_value_t *) ((frame_ctx_p) + 1))[i])
 
+/**
+ * Get the executable object.
+ */
+#define VM_GET_EXECUTABLE_OBJECT(frame_ctx_p) \
+  ((ecma_extended_object_t *) ((uintptr_t) (frame_ctx_p) - (uintptr_t) offsetof (vm_executable_object_t, frame_ctx)))
+
 /**
  * Generator frame context.
  */