fix no RHS in class properties causing undefined to be used instead of a noop - fixes #1396

src/babel/transformation/templates/helper-create-decorated-class.js

@@ -24,7 +24,7 @@
           }
         }
 
-        if (descriptor.initializer) {
+        if (descriptor.initializer !== undefined) {
           initializers[key] = descriptor;
           continue;
         }

src/babel/transformation/templates/helper-create-decorated-object.js

@@ -26,9 +26,10 @@
       }
     }
 
-    descriptor.value = descriptor.initializer.call(target);
-
-    Object.defineProperty(target, key, descriptor);
+    if (descriptor.initializer) {
+      descriptor.value = descriptor.initializer.call(target);
+      Object.defineProperty(target, key, descriptor);
+    }
   }
 
   return target;

src/babel/transformation/templates/helper-define-decorated-property-descriptor.js

@@ -6,6 +6,7 @@
   for (var _key in _descriptor) descriptor[_key] = _descriptor[_key];
 
   // initialize it
+  if (!descriptor.initializer) return;
   descriptor.value = descriptor.initializer.call(target);
 
   Object.defineProperty(target, key, descriptor);

src/babel/transformation/transformers/es6/classes.js

@@ -550,8 +550,12 @@ class ClassTransformer {
 
     if (node.decorators) {
       var body = [];
-      if (node.value) body.push(t.returnStatement(node.value));
-      node.value = t.functionExpression(null, [], t.blockStatement(body));
+      if (node.value) {
+        body.push(t.returnStatement(node.value));
+        node.value = t.functionExpression(null, [], t.blockStatement(body));
+      } else {
+        node.value = t.literal(null);
+      }
       this.pushToMap(node, true, "initializer");
 
       var initializers;
@@ -575,7 +579,7 @@ class ClassTransformer {
         ])
       ));
     } else {
-      node.value = node.value || t.identifier("undefined");
+      if (!node.value && !node.decorators) return;
 
       if (node.static) {
         // can just be added to the static map