ChakraCore in a browser

Splitting out of the conversation started by @lmcdougald in https://github.com/chakra-core/ChakraCore/issues/6616#issuecomment-789492298:

> Well, EdgeHTML isn't going anywhere from what we know. It'd be interesting to see how much work would be needed to drop ChakraCore in to replace KJS in KHTML (yes, old, but open and provably can be extended into a modern browser).

Also from @curtisman in https://github.com/chakra-core/ChakraCore/issues/6616#issuecomment-792391375:

> ChakraCore should have most of what you need to run with modern browser. I did a quick hacky prototype that shim's v8 API (similar to the shim that enables node-chakra) and able to run Chromium with pretty good perf. Most of the additional code to wire up with any HTML engines deals with projecting the DOM into the JS context and memory management between the two sides.

In my personal view this would be a very valuable experiment - running the engine inside of a browser unlocks a great variety of non-trivial workloads.

Read the linked discussion in issue 6616 and the ChakraCore C API documentation first. Investigate the mentioned KHTML and Chromium integration ideas, including DOM projection and memory management between the HTML engine and JavaScript context. The issue does not define a concrete implementation or completion test.

Written by the indexing model from the issue text.