Fix spelling of convertible
Fix spelling of convertible

minestarks/TypeScript,Microsoft/TypeScript,kitsonk/TypeScript,alexeagle/TypeScript,microsoft/TypeScript,minestarks/TypeScript,RyanCavanaugh/TypeScript,SaschaNaz/TypeScript,SaschaNaz/TypeScript,microsoft/TypeScript,weswigham/TypeScript,weswigham/TypeScript,microsoft/TypeScript,alexeagle/TypeScript,kpreisser/TypeScript,RyanCavanaugh/TypeScript,SaschaNaz/TypeScript,kitsonk/TypeScript,nojvek/TypeScript,kitsonk/TypeScript,nojvek/TypeScript,Microsoft/TypeScript,SaschaNaz/TypeScript,kpreisser/TypeScript,alexeagle/TypeScript,RyanCavanaugh/TypeScript,weswigham/TypeScript,minestarks/TypeScript,Microsoft/TypeScript,nojvek/TypeScript,kpreisser/TypeScript,nojvek/TypeScript