Add WebAssembly port of N-API#2

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OhadRau wants to merge 3 commits intofeat/v8-embedder-builtinsfrom

feat/wasm-napi-port

Commits on Aug 1, 2019

Add WASM port of NAPI
Ohad Rau
committed
Implement WASM callbacks for NAPI properties
Ohad Rau
committed

Commits on Aug 2, 2019

Cleanup wasm node api
Ohad Rau
committed