New jerry_get_symbol_description API function (#4206)

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

docs/02.API-REFERENCE.md

@@ -3996,6 +3996,68 @@ main (void)
 
 - [jerry_well_known_symbol_t](#jerry_well_known_symbol_t)
 
+## jerry_get_symbol_description
+
+**Summary**
+
+Returns with the `[[Description]]` internal property of a symbol value.
+
+*Notes*:
+- Returned value must be freed with [jerry_release_value](#jerry_release_value) when it
+  is no longer needed.
+- This API depends on a build option (`JERRY_BUILTIN_SYMBOL`) and can be checked
+  in runtime with the `JERRY_FEATURE_SYMBOL` feature enum value,
+  see: [jerry_is_feature_enabled](#jerry_is_feature_enabled).
+- The es.next profile enables this by default.
+- If the symbol support is not enabled an error will be returned.
+
+**Prototype**
+
+```c
+jerry_value_t
+jerry_get_symbol_description (const jerry_value_t value);
+```
+
+- `value` - symbol value
+- return value
+  - string or undefined value containing the symbol's description - if success
+  - thrown error, otherwise
+
+*New in version [[NEXT_RELEASE]]*.
+
+**Example**
+
+[doctest]: # ()
+
+```c
+#include "jerryscript.h"
+
+int
+main (void)
+{
+  jerry_init (JERRY_INIT_EMPTY);
+
+  jerry_value_t string_value = jerry_create_string ((const jerry_char_t *) "foo");
+  jerry_value_t symbol_value = jerry_create_symbol (string_value);
+
+  jerry_release_value (string_value);
+
+  jerry_value_t symbol_description = jerry_get_symbol_description (symbol_value);
+
+  // usage of symbol_desc_string
+
+  jerry_release_value (symbol_description);
+  jerry_release_value (symbol_value);
+
+  jerry_cleanup ();
+  return 0;
+}
+```
+
+**See also**
+
+- [jerry_get_symbol_descriptive_string](#jerry_get_symbol_descriptive_string)
+
 ## jerry_get_symbol_descriptive_string
 
 **Summary**
@@ -4055,6 +4117,10 @@ main (void)
 }
 ```
 
+**See also**
+
+- [jerry_get_symbol_description](#jerry_get_symbol_description)
+
 # Functions for BigInts
 
 These APIs all depend on build option (`JERRY_BUILTIN_BIGINT`).