Private class methods stage 3 (#8654)

* Add private method syntax support

* Add private method spec support

* Add private method loose support

* Throw error if static private method is used

* Add more isStatic & isMethod checks

* Remove `writable:false` from private method inits

`writable` is false by default.

* Add private method func obj equality check

* Throw if private accessor is used

* Add check for fields === private method loose mode

* Throw buildCodeFrameErrors instead of Errors

* Move obj destructuring inside for loop

* Remove "computed" from ClassPrivateMethod type def

packages/babel-generator/src/generators/classes.js

@@ -140,6 +140,12 @@ export function ClassMethod(node: Object) {
   this.print(node.body, node);
 }
 
+export function ClassPrivateMethod(node: Object) {
+  this._classMethodHead(node);
+  this.space();
+  this.print(node.body, node);
+}
+
 export function _classMethodHead(node) {
   this.printJoin(node.decorators, node);