message: Kill off another Flow error in getDefinition
  Down to 139 errors with this change.
diff: @@ -18,6 +18,7 @@ import type {
  Definition,
  DefinitionQueryResult,
  FragmentInfo,
  + Position,
  Range,
  Uri,
  } from 'graphql-language-service-types';
  @@ -32,6 +33,12 @@ function getRange(text: string, node: ASTNode): Range {
  return locToRange(text, location);
  }
  +function getPosition(text: string, node: ASTNode): Position {
  + const location = node.loc;
  + invariant(location, 'Expected ASTNode to have a location.');
  + return offsetToPosition(text, location.start);
  +}
  +
  export async function getDefinitionQueryResultForFragmentSpread(
  text: string,
  fragment: FragmentSpreadNode,
  @@ -75,7 +82,7 @@ function getDefinitionForFragmentDefinition(
  ): Definition {
  return {
  path,
  - position: offsetToPosition(text, definition.name.loc.start),
  + position: getPosition(text, definition.name),
  range: getRange(text, definition),
  name: definition.name.value,
  language: LANGUAGE,
  