Revise ES2015 feature guards (#3240)

All the basic language element guards are merged into JERRY_ES2015 macro guard.

JerryScript-DCO-1.0-Signed-off-by: Robert Fancsik frobert@inf.u-szeged.hu

jerry-core/ecma/builtin-objects/ecma-builtin-symbol.c

@@ -27,7 +27,7 @@
  #include "jcontext.h"
  #include "jrt.h"
 
-#if ENABLED (JERRY_ES2015_BUILTIN_SYMBOL)
+#if ENABLED (JERRY_ES2015)
 
 #define ECMA_BUILTINS_INTERNAL
 #include "ecma-builtins-internal.h"
@@ -243,4 +243,4 @@ ecma_builtin_symbol_key_for (ecma_value_t this_arg, /**< this argument */
  * @}
  */
 
-#endif /* ENABLED (JERRY_ES2015_BUILTIN_SYMBOL) */
+#endif /* ENABLED (JERRY_ES2015) */