Issue #18665: fix typos. Patch by Vajrasky Kok.

Include/frameobject.h

@@ -36,7 +36,7 @@ typedef struct _frame {
            non-generator frames. See the save_exc_state and swap_exc_state
            functions in ceval.c for details of their use. */
     PyObject *f_exc_type, *f_exc_value, *f_exc_traceback;
-    /* Borrowed referenced to a generator, or NULL */
+    /* Borrowed reference to a generator, or NULL */
     PyObject *f_gen;
 
     PyThreadState *f_tstate;

Lib/test/test_frame.py

@@ -96,7 +96,7 @@ class ClearTest(unittest.TestCase):
 
     @support.cpython_only
     def test_clear_refcycles(self):
-        # .clear() doesn't leave any refcycle behin
+        # .clear() doesn't leave any refcycle behind
         with support.disable_gc():
             class C:
                 pass