Simplify incremental parsing by moving old source tree nodes before doing anything.
Fix interface.
Simplify parser initializer.
Simplify incremental code.
Always mark nodes and tokens that cross the edited range.
Slightly speed up marking by avoiding calling fullStart on so many nodes and tokens.
Simplify incremental parser.
Speed up incremental parser.
Make 'kind' non-enumerable.
Remove unused asserts.
Fixing check.
Simplify rewind points.
Rename context flag.
Move 'disallowIn' into being an ambient parser context flag.

This greatly simplifies how we will do incremental parsing.
Reduce lambda allocations in the parser.
Merge pull request #1258 from Microsoft/parserContextFlags

Change 'disallowIn' into an ambient parser context flag.
Merge pull request #1239 from Microsoft/incrementalParser

Change how the incremental parser works.
Merge remote-tracking branch 'ts_official/master'