[clang][AST] createNestedNameSpecifierForScopeOf - don't use dyn_cast_or_null on never null DC argument

Fixes static analysis warning about later dereferencing the DC variable which might have been null (assumed due to dyn_cast_or_null) - getRedeclContext shouldn't ever return a null value so safe to use dyn_cast instead.

Author: RKSimon

clang/lib/AST/QualTypeNames.cpp

@@ -270,8 +270,8 @@ static NestedNameSpecifier *createNestedNameSpecifierForScopeOf(
   assert(Decl);
 
   const DeclContext *DC = Decl->getDeclContext()->getRedeclContext();
-  const auto *Outer = dyn_cast_or_null<NamedDecl>(DC);
-  const auto *OuterNS = dyn_cast_or_null<NamespaceDecl>(DC);
+  const auto *Outer = dyn_cast<NamedDecl>(DC);
+  const auto *OuterNS = dyn_cast<NamespaceDecl>(DC);
   if (Outer && !(OuterNS && OuterNS->isAnonymousNamespace())) {
     if (const auto *CxxDecl = dyn_cast<CXXRecordDecl>(DC)) {
       if (ClassTemplateDecl *ClassTempl =