Run the [`fixtures/ssr` test harness](https://github.com/facebook/react/tree/master/fixtures/ssr). In the terminal, the following warning is logged:

```
Warning: Unknown prop `onClick` on <a> tag. Remove this prop from the element. For details, see https://fb.me/react-unknown-prop
  in a (at Page.js:12)
  in p (at Page.js:18)
  in div (at Page.js:17)
  in Page (at App.js:12)
  in div (at App.js:10)
  in body (at Chrome.js:17)
  in html (at Chrome.js:9)
  in Chrome (at App.js:9)
  in App (at render.js:18)
```

SSR behavior should match client-side behavior and not warn for a valid attribute.
onFocusIn: true,
    onFocusOut: true,
  };
  var warnedProperties = {};
  var validateProperty = function(tagName, name, debugID) {
    if (
      DOMProperty.properties.hasOwnProperty(name) ||
      DOMProperty.isCustomAttribute(name)
    ) {
      return true;
    }
    if (
      (reactProps.hasOwnProperty(name) && reactProps[name]) ||
      (warnedProperties.hasOwnProperty(name) && warnedProperties[name])
    ) {
      return true;
    }
    if (EventPluginRegistry.registrationNameModules.hasOwnProperty(name)) {
      return true;
    }
    warnedProperties[name] = true;
    var lowerCasedName = name.toLowerCase();
    
    var standardName = DOMProperty.isCustomAttribute(lowerCasedName)
      ? lowerCasedName
      : DOMProperty.getPossibleStandardName.hasOwnProperty(lowerCasedName)
          ? DOMProperty.getPossibleStandardName[lowerCasedName]
          : null;
    var registrationName = EventPluginRegistry.possibleRegistrationNames.hasOwnProperty(
      lowerCasedName,