Use after free in Neon external buffers
Neon provides functionality for creating JavaScript `ArrayBuffer` (and the `Buffer` subtype) instances backed by bytes allocated outside of V8/Node. The [`JsArrayBuffer::external`](https://docs.rs/neon/0.10.0/neon/types/struct.JsArrayBuffer.html#method.external) and [`JsBuffer::external`](https://docs.rs/neon/0.10.0/neon/types/struct.JsBuffer.html#method.external) did not require `T: 'static` prior to Neon `0.10.1`. This allowed creating an externally backed buffer from types that may be freed while they are still referenced by a JavaScript `ArrayBuffer`.The following example demonstrates use after free. It compiles on versions `<0.10.1` and fails to compile afterward.