Add support for new.target (#3469)

Notable changes:
* Extracted the pure JS/builtin and external C method invocations
  into two new methods (`ecma_op_function_call_{simple, external}`).
* Updated parser/scanner to handle "new.target" correctly.
* Added JS test case.

JerryScript-DCO-1.0-Signed-off-by: Peter Gal pgal.u-szeged@partner.samsung.com

jerry-core/parser/js/js-parser-util.c

@@ -1181,6 +1181,14 @@ parser_error_to_string (parser_error_t error) /**< error code */
     {
       return "Rest parameter may not have a default initializer.";
     }
+    case PARSER_ERR_NEW_TARGET_EXPECTED:
+    {
+      return "Expected new.target expression.";
+    }
+    case PARSER_ERR_NEW_TARGET_NOT_ALLOWED:
+    {
+      return "new.target expression is not allowed here.";
+    }
 #endif /* ENABLED (JERRY_ES2015) */
 #if ENABLED (JERRY_ES2015_MODULE_SYSTEM)
     case PARSER_ERR_FILE_NOT_FOUND: