var
  wHandle: HWND;
begin
  try
    CoInitialize(nil);

    FillChar(WndClass, SizeOf(WndClass), 0);
    with WndClass do
    begin
      cbSize := SizeOf(WndClass);
      lpszClassName := 'MESSAGE_ONLY_WINDOW'; //PWideChar('STATIC'); 
      lpfnWndProc := @DefWindowProc;
    end;
    RegisterClassEx(WndClass);

    wHandle := CreateWindowEx(0, WndClass.lpszClassName, nil,
      0, 0, 0, 0, 0, DWORD(HWND_MESSAGE), 0, 0, nil);
    if (wHandle = 0) then //<- тут всегда 0 когда x64
      raise Exception.Create('CreateWindowEx');

    if (CoCreateInstance(CLSID_InternetExplorer, nil, CLSCTX_INPROC_SERVER,
      IID_IWebBrowser2, wb) <> S_OK) then
      raise Exception.Create('CoCreateInstance');

      AtlAxAttachControl(wb, wHandle, nil);
...

function httpByWebBrowser(const aURL: string): string;
var
  WB: IWebBrowser2; // TWebBrowser;
  DT: TDateTime;
  wHandle: HWND;
  T: String;
var
  WndClass: TWndClassEx;

  function WB_GetHTMLCode(WebBrowser: IWebBrowser2; var ACode: String): boolean;
  var
    ps: IPersistStreamInit;
    ss: TStringStream;
    sa: IStream;
    s: string;

  begin
    s := '';
    ss := TStringStream.Create(s);
    ps := WebBrowser.Document as IPersistStreamInit;
    try
      sa := TStreamAdapter.Create(ss, soReference) as IStream;
      Result := Succeeded(ps.Save(sa, True));
      if Result then
        ACode := UTF8ToString(ss.Datastring);
    finally
      ss.Free;
    end;
  end;

  procedure ProcessMessage(wHandle: HWND);
  var
    Msg: TMsg;
  begin
    while PeekMessage(Msg, 0, 0, 0, PM_REMOVE) do
    begin
      TranslateMessage(Msg);
      DispatchMessage(Msg);
    end;
  end;

begin
  try
    CoInitialize(nil);

    FillChar(WndClass, SizeOf(WndClass), 0);
    with WndClass do
    begin
      cbSize := SizeOf(WndClass);
      lpszClassName := PWideChar('STATIC'); // MESSAGE_ONLY_WINDOW
      lpfnWndProc := @DefWindowProc;
    end;
    RegisterClassEx(WndClass);

    wHandle := CreateWindowEx(0, WndClass.lpszClassName, nil, 0, 0, 0, 0, 0, DWORD(HWND_MESSAGE), 0, 0, nil);
    if (wHandle = 0) then
    begin
      raise Exception.Create('CreateWindowEx'#13#10 + IntToStr(GetLastError));
    end;

    if (CoCreateInstance(CLSID_InternetExplorer, nil, CLSCTX_INPROC_SERVER, IID_IWebBrowser2, WB) <> S_OK) then
      raise Exception.Create('CoCreateInstance');

    AtlAxAttachControl(WB, wHandle, nil);

    DT := Now();
    WB.Silent := True;
    WB.Navigate(aURL, EmptyParam, EmptyParam, EmptyParam, EmptyParam);

    while (WB.ReadyState <> READYSTATE_COMPLETE) and (SecondsBetween(Now(), DT) < 15) do
    begin
      ProcessMessage(wHandle);
      Sleep(10);
    end;
    T := '';
    if SecondsBetween(Now(), DT) < 12 then
      WB_GetHTMLCode(WB, T);
    Result := T;

  finally
    WB := nil;
    DestroyWindow(wHandle);
    CoUninitialize;
  end;
end;