Optimize LCache operation.

The cache stores only real properties now, because storing NULLs has
little benefit according to tests. Since only real properties are
stored now, there is no need to create real references to objects
and property names, which reduces the keeping of dead objects after
garbage collection.

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

jerry-core/ecma/base/ecma-gc.c

@@ -583,8 +583,6 @@ ecma_try_to_give_back_some_memory (jmem_try_give_memory_back_severity_t severity
     JERRY_ASSERT (severity == JMEM_TRY_GIVE_MEMORY_BACK_SEVERITY_HIGH);
 
     /* Freeing as much memory as we currently can */
-    ecma_lcache_invalidate_all ();
-
     ecma_gc_run ();
   }
 } /* ecma_try_to_give_back_some_memory */