Remove whitespace generation (#5833)

* 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

packages/babel-generator/test/fixtures/flowUsesCommas/ObjectExpression/expected.js

@@ -1,10 +1,39 @@
-var a: { numVal: number };
-var a: { numVal: number };
-var a: { numVal: number, [indexer: string]: number, };
-var a: ?{ numVal: number };
-var a: { numVal: number, strVal: string, };
-var a: { subObj: { strVal: string } };
-var a: { subObj: ?{ strVal: string } };
-var a: { param1: number, param2: string, };
-var a: { param1: number, param2?: string, };
-var a: { [a: number]: string, [b: number]: string, };
+var a: {
+  numVal: number
+};
+var a: {
+  numVal: number
+};
+var a: {
+  numVal: number,
+  [indexer: string]: number,
+};
+var a: ?{
+  numVal: number
+};
+var a: {
+  numVal: number,
+  strVal: string,
+};
+var a: {
+  subObj: {
+    strVal: string
+  }
+};
+var a: {
+  subObj: ?{
+    strVal: string
+  }
+};
+var a: {
+  param1: number,
+  param2: string,
+};
+var a: {
+  param1: number,
+  param2?: string,
+};
+var a: {
+  [a: number]: string,
+  [b: number]: string,
+};