user/src/com/google/gwt/user/Hyperlink.gwt.xml

<module>
  <inherits name="com.google.gwt.core.Core"/>
  <inherits name="com.google.gwt.user.UserAgent"/>

  <replace-with class="com.google.gwt.user.client.ui.impl.HyperlinkImplSafari">
    <when-type-is class="com.google.gwt.user.client.ui.impl.HyperlinkImpl"/>
    <when-property-is name="user.agent" value="safari"/>
  </replace-with>
</module>