Enable more babylon plugins (#220)

* Enable more babylon plugins

* Add pipelineOperator

* Add nullishCoalescingOperator

Author: Vlad Zhukov

src/babylon.js

@@ -21,11 +21,21 @@ var options = {
     'objectRestSpread',
     'decorators',
     'classProperties',
+    'classPrivateProperties',
+    'classPrivateMethods',
     'exportExtensions',
     'asyncGenerators',
     'functionBind',
     'functionSent',
     'dynamicImport',
+    'numericSeparator',
+    'optionalChaining',
+    'importMeta',
+    'bigInt',
+    'optionalCatchBinding',
+    'throwExpressions',
+    'pipelineOperator',
+    'nullishCoalescingOperator',
   ],
 };