Cleanup: Grammar in comments

- it's self vs. itself
- boiler plate vs boilerplate

source/blender/blenlib/tests/BLI_string_test.cc

@@ -1390,7 +1390,7 @@ class StringEscape : public testing::Test {
     size_t dst_test_len;
     char dst_test[64]; /* Must be big enough for all input. */
     for (const auto &item : items) {
-      /* Validate the static size is big enough (test the test it's self). */
+      /* Validate the static size is big enough (test the test itself). */
       EXPECT_LT((strlen(item[0]) * 2) + 1, sizeof(dst_test));
       /* Escape the string. */
       dst_test_len = BLI_str_escape(dst_test, item[0], sizeof(dst_test));

source/blender/python/intern/bpy_interface_atexit.cc

@@ -33,7 +33,7 @@ static PyObject *bpy_atexit(PyObject * /*self*/, PyObject * /*args*/, PyObject *
    */
 
   bContext *C = BPY_context_get();
-  /* As Python requested the exit, it handles shutting it's self down. */
+  /* As Python requested the exit, it handles shutting itself down. */
   const bool do_python_exit = false;
   /* User actions such as saving the session, preferences, recent-files for e.g.
    * should be skipped because an explicit call to exit is more likely to be used as part of

tests/python/ui_simulate/run_blender_setup.py

@@ -4,7 +4,7 @@
 
 """
 Utility script, called by ``run.py`` to run inside Blender,
-to avoid boiler plate code having to be added into each test.
+to avoid boilerplate code having to be added into each test.
 """
 
 import os
@@ -64,7 +64,7 @@ def main():
     parser = create_parser()
     args = parser.parse_args(sys.argv[sys.argv.index("--") + 1:])
 
-    # Check if `bpy.app.use_event_simulate` has been enabled by the test it's self.
+    # Check if `bpy.app.use_event_simulate` has been enabled by the test itself.
     # When writing tests, it's useful if the test can temporarily be set to keep the window open.
 
     def on_error():

tools/utils/blender_theme_as_c.py

@@ -138,7 +138,7 @@ def dna_rename_defs(blend):
         for (member_storage, member_runtime) in members:
             struct_name_storage = struct_runtime_to_storage_map.get(struct_name_runtime, struct_name_runtime)
             struct_name_storage = struct_name_storage.encode('utf-8')
-            # The struct it's self may have been renamed.
+            # The struct itself may have been renamed.
             member_storage = member_storage.encode('utf-8')
             member_runtime = member_runtime.encode('utf-8')
             dna_struct = blend.structs[blend.sdna_index_from_id[struct_name_storage]]