Improve handling of non default DPI in wxHtmlWindow deawing code

This replaces the fix of f4dcac9f44 (Return wxFont adjusted to DPI in
wxHtmlWinParser::CreateCurrentFont(), 2020-11-25) adjusting the font
explicitly under MSW with a better fix, associating the correct window
(and hence DPI) with the device context used in OnPaint().

See #18564.

src/html/htmlwin.cpp

@@ -1116,6 +1116,7 @@ void wxHtmlWindow::OnPaint(wxPaintEvent& WXUNUSED(event))
         dc = &dcm;
     }
 
+    dc->GetImpl()->SetWindow(this);
     PrepareDC(*dc);
 
     // Erase the background: for compatibility, we must generate the event to

src/html/winpars.cpp

@@ -619,10 +619,6 @@ wxFont* wxHtmlWinParser::CreateCurrentFont()
         *encptr = m_OutputEnc;
 #endif
     }
-#ifdef __WXMSW__
-    if ( m_windowInterface && m_windowInterface->GetHTMLWindow() )
-        (*fontptr)->WXAdjustToPPI(m_windowInterface->GetHTMLWindow()->GetDPI());
-#endif
     m_DC->SetFont(**fontptr);
     return (*fontptr);
 }