title: builder (android.content.context) in builder cannot be applied to Activity
body: <p>I'm trying to load web page inside of webview.the webview load inside the Dialog.i'm tried this code.but show the error <code>builder (android.content.context) in builder cannot be applied to ..</code> and underline <code>this</code> in red line.</p>
  
  <pre><code>protected void onCreate(Bundle savedInstanceState) {
          super.onCreate(savedInstanceState);
          setContentView(R.layout.activity_main);
  
      webview=(WebView)findViewById(R.id.webview);
      webview.setWebViewClient(new WebViewClient();
      webview.loadUrl("http://example.com/abc.html");
      AlertDialog.Builder dialog = new AlertDialog.Builder(this);
      dialog.setView(webview);
      dialog.setPositiveButton("Okay", null);
      dialog.show();
  }
  </code></pre>