| Additional IP Rights Grant (Patents) | 
 |  | 
 | "This implementation" means the copyrightable works distributed by | 
 | Google as part of the Dart Project. | 
 |  | 
 | Google hereby grants to you a perpetual, worldwide, non-exclusive, | 
 | no-charge, royalty-free, irrevocable (except as stated in this | 
 | section) patent license to make, have made, use, offer to sell, sell, | 
 | import, transfer, and otherwise run, modify and propagate the contents | 
 | of this implementation of Dart, where such license applies only to | 
 | those patent claims, both currently owned by Google and acquired in | 
 | the future, licensable by Google that are necessarily infringed by | 
 | this implementation of Dart. This grant does not include claims that | 
 | would be infringed only as a consequence of further modification of | 
 | this implementation. If you or your agent or exclusive licensee | 
 | institute or order or agree to the institution of patent litigation | 
 | against any entity (including a cross-claim or counterclaim in a | 
 | lawsuit) alleging that this implementation of Dart or any code | 
 | incorporated within this implementation of Dart constitutes direct or | 
 | contributory patent infringement, or inducement of patent | 
 | infringement, then any patent rights granted to you under this License | 
 | for this implementation of Dart shall terminate as of the date such | 
 | litigation is filed. |