* Remove whitespace generation and rely on default printing
Changes to printing:
* Add newline after last empty SwitchCase
* Add newlines around block comments if they are non-flow comments or contain newlines
* Fix a few more fixtures
* avoid duplicating impure initializers in object rest destructuring
* reuse existing VariableDeclarations in object rest destructuring, to fix two issues:
1. inserting an additional VariableDeclaration after the current one may change order of operations, which is unsafe if a future VariableDeclarator refers to a destructured variable.
2. The entire VariableDeclaration is removed when all properties are rest properties, indiscriminately removing other variables
