function resolveUnionTypeAnnotation(node){// Go through all the union and resolve any generic types.
return node.types.map(function(annotation){if(annotation.type==='GenericTypeAnnotation'){return resolveGenericTypeAnnotation(annotation);}return annotation;});}
Tries to find the definition of a GenericTypeAnnotation in the current scope.
@param  {ASTNode}      node The node GenericTypeAnnotation node to resolve.
@return {ASTNode|null}      Return null if definition cannot be found, ASTNode otherwise.