[AST][NFC] Fixes a comment typo

Also a test for commit access.
diff --git a/clang/lib/AST/DeclCXX.cpp b/clang/lib/AST/DeclCXX.cpp
index 12ec44f..58b50de 100644
--- a/clang/lib/AST/DeclCXX.cpp
+++ b/clang/lib/AST/DeclCXX.cpp
@@ -413,7 +413,7 @@
       data().HasIrrelevantDestructor = false;
 
     // C++11 [class.copy]p18:
-    //   The implicitly-declared copy assignment oeprator for a class X will
+    //   The implicitly-declared copy assignment operator for a class X will
     //   have the form 'X& X::operator=(const X&)' if each direct base class B
     //   of X has a copy assignment operator whose parameter is of type 'const
     //   B&', 'const volatile B&', or 'B' [...]