Rename the jerry_value_has_error_flag function. (#2290)

Rename the function to represent it's real functionality.

JerryScript-DCO-1.0-Signed-off-by: Istvan Miklos imiklos2@inf.u-szeged.hu

docs/06.REFERENCE-COUNTING.md

@@ -61,7 +61,7 @@ behaviour through property getting and setting.
    * prop_value contains a live reference to an error object.
    * This reference must be released as well. */
 
-  if (jerry_value_has_error_flag (prop_value))
+  if (jerry_value_is_error (prop_value))
   {
     /* Errors can be handled here. */
   }
@@ -93,7 +93,7 @@ behaviour through property getting and setting.
   /* The reference stored in the 'result' variable is live whether
    * the operation is successful or not, and must also be freed. */
 
-  if (jerry_value_has_error_flag (result))
+  if (jerry_value_is_error (result))
   {
     /* Errors can be handled here. */
   }