[SwiftREPL] Registter typechecker & friends only once.

<rdar://problem/56483355>

Author: Davide Italiano

lldb/source/Plugins/ExpressionParser/Swift/SwiftREPL.cpp

@@ -553,10 +553,6 @@ int SwiftREPL::CompleteCode(const std::string &current_code,
         llvm::dyn_cast_or_null<SwiftASTContext>(&*type_system_or_err);
     if (target_swift_ast)
       m_swift_ast_sp.reset(new SwiftASTContext(*target_swift_ast));
-    auto &ctx = *m_swift_ast_sp.get()->GetASTContext();
-    swift::registerIDERequestFunctions(ctx.evaluator);
-    swift::registerTypeCheckerRequestFunctions(ctx.evaluator);
-    swift::createTypeChecker(ctx);
   }
   SwiftASTContext *swift_ast = m_swift_ast_sp.get();
 

lldb/source/Symbol/SwiftASTContext.cpp

@@ -3467,6 +3467,7 @@ swift::ASTContext *SwiftASTContext::GetASTContext() {
 
   // Set up the required state for the evaluator in the TypeChecker.
   (void)swift::createTypeChecker(*m_ast_context_ap);
+  registerIDERequestFunctions(m_ast_context_ap->evaluator);
   registerParseRequestFunctions(m_ast_context_ap->evaluator);
   registerTypeCheckerRequestFunctions(m_ast_context_ap->evaluator);