This usually means that the user mixed up our lowercase/uppercase naming convention; see https://github.com/facebook/react/pull/3429#issuecomment-85166440.

We could add a message like

> Warning: The tag <commentBox> is unrecognized in this browser. If you meant to render a React component, start its name with an uppercase letter.

We'd check this only once per tag and only in development mode.

Object.freeze(nextProp);
          }
        }
        if (lastProp) {
          
          for (styleName in lastProp) {
            if (
              lastProp.hasOwnProperty(styleName) &&
              (!nextProp || !nextProp.hasOwnProperty(styleName))
            ) {
              styleUpdates = styleUpdates || {};
              styleUpdates[styleName] = '';
            }
          }
          
          for (styleName in nextProp) {
            if (
              nextProp.hasOwnProperty(styleName) &&
              lastProp[styleName] !== nextProp[styleName]
            ) {
              styleUpdates = styleUpdates || {};
              styleUpdates[styleName] = nextProp[styleName];
            }
          }
        } else {
          
          styleUpdates = nextProp;
        }
      } else if (registrationNameModules.hasOwnProperty(propKey)) {
        if (nextProp) {