Properly emit 'void 0' when emitting destructuring assignments.
Merge pull request #1464 from Microsoft/void0

Properly emit 'void 0' when emitting destructuring assignments.
Resurrect the post edit invariants checking for fourslash.
Don't emit error flags in the 262 baselines unless the node actually had an error.

This helps reduce clutter.
Rename some locals.
In Fourslash: Compare ASTs for files produced incrementally versus files produced with a full parse.
Avoid lookahead when parsing a statement.

If a statement started with an identifier, then we'd normally lookahead to see if the next token
was a colon.  Lookahead is expensive (as it has to rescan tokens).  Instead, we do the same thing
we do for arrow-functions.  We just parse out the identifier, and afterwards we check if there is
a colon as the current token.  Now, no lookahead is required.
Merge branch 'master' into postEditInvariants

Conflicts:
	src/harness/test262Runner.ts
Merge pull request #1465 from Microsoft/labeledStatement

Avoid lookahead when parsing a statement.
Merge pull request #1467 from Microsoft/postEditInvariants

Resurrect the post edit invariants checking for fourslash.
Update LKG.
Simplify 262 baselines.
Merge pull request #1468 from Microsoft/LKG

Update LKG.
Merge pull request #1469 from Microsoft/262baselines

Simplify 262 baselines.
Make utility mehtod names clearer.
Merge pull request #1470 from Microsoft/flagAggregation

Make utility method names clearer.
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.