Remove string copy

Changed 'ecma_copy_or_ref_ecma_string' to 'ecma_ref_ecma_string'. It does
not copy the string if the maximum number of reference counter is reached,
but bails out with an error like the 'ecma_ref_object' function does.

JerryScript-DCO-1.0-Signed-off-by: László Langó llango.u-szeged@partner.samsung.com

jerry-core/ecma/operations/ecma-string-object.c

@@ -142,7 +142,7 @@ ecma_op_string_object_get_own_property (ecma_object_t *obj_p, /**< a String obje
   {
     uint32_index = property_name_p->u.uint32_number;
 
-    new_prop_name_p = ecma_copy_or_ref_ecma_string (property_name_p);
+    new_prop_name_p = ecma_ref_ecma_string (property_name_p);
   }
   else
   {