Move test helpers into the harness Utils module.
Don't convert the tree to JSON before checking it.  Just check it directly.
Check post edit invariants after every edit.
Always run all fourslash tests in high fidelity typing mode.

We want to verify after every edit that our incremental data is correct.
Ensure the 'hasParseErrors' bit is the same between trees.
Check tree invariants during fourslash tests.
Formatting.
Update timeout to 6 seconds.
Merge branch 'master' into typingHighFidelity
Up timeout to 20 seconds.

A specific test "genericRespecialization1" takes quite some time on travis (though only a couple
of seconds locally).
Merge pull request #1482 from Microsoft/typingHighFidelity

Move test helpers into the harness Utils module.