* Don't show "context" for classes without either contextType or contextTypes
* For classes with contextTypes, change the label to "legacy context" instead

---
Originally reported by @gaearon via https://github.com/bvaughn/react-devtools-experimental/issues/368
instance.constructor &&
            instance.constructor.contextType != null
          ) {
            modernContext = instance.context;
          } else {
            legacyContext = instance.context;
            if (legacyContext && Object.keys(legacyContext).length === 0) {
              legacyContext = NO_CONTEXT;
            }
          }
        }
        return [legacyContext, modernContext];
      default:
        return null;
    }
  }
   R
   F
   s
  function crawlToInitializeContextsMap(fiber: Fiber) {
    updateContextsForFiber(fiber);
    let current = fiber.child;
    while (current !== null) {
      crawlToInitializeContextsMap(current);
      current = current.sibling;
    }
  }
  function getContextChangedKeys(fiber: Fiber): null | boolean | Array<string> {
    switch (getElementTypeForFiber(fiber)) {