Fix identity check on type_or_implicit in Flow_ast_mapper
Fix identity check on type_or_implicit in Flow_ast_mapper

Summary: It fixes one diffing issue with calls and new that contained a type hint, like `createComponent<MyComponent>(...)`. As a new object was created regardless of whether the type was mapped, the reference-based diffing algorithm would consider it a new node.

Reviewed By: panagosg7

Differential Revision: D10381139

fbshipit-source-id: 25200b041ce14519dc732a8cb772e2d63366e795

nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow,nmote/flow