Support static snapshots. (#2239)

Unlike normal snapshots, no part of a static snapshot is loaded into
the RAM when executed from ROM. Static snapshots rely heavily on
external magic strings.

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

jerry-core/ecma/base/ecma-helpers-value.c

@@ -311,6 +311,18 @@ ecma_is_value_string (ecma_value_t value) /**< ecma value */
   return ((value & (ECMA_VALUE_TYPE_MASK - 0x4)) == ECMA_TYPE_STRING);
 } /* ecma_is_value_string */
 
+/**
+ * Check if the value is direct_ecma-string.
+ *
+ * @return true - if the value contains ecma-string value,
+ *         false - otherwise
+ */
+inline bool __attr_const___ __attr_always_inline___
+ecma_is_value_direct_string (ecma_value_t value) /**< ecma value */
+{
+  return (ecma_get_value_type_field (value) == ECMA_TYPE_DIRECT_STRING);
+} /* ecma_is_value_direct_string */
+
 /**
  * Check if the value is object.
  *