diff --git a/src/components/script/dom/bindings/codegen/CodegenRust.py b/src/components/script/dom/bindings/codegen/CodegenRust.py
index a5e43e69755..069254b7c16 100644
--- a/src/components/script/dom/bindings/codegen/CodegenRust.py
+++ b/src/components/script/dom/bindings/codegen/CodegenRust.py
@@ -551,10 +551,6 @@ def getJSToNativeConversionTemplate(type, descriptorProvider, failureCode=None,
         raise TypeError("Can't handle sequence arguments yet")
 
     if type.isUnion():
-        if isMember:
-            raise TypeError("Can't handle unions as members, we have a "
-                            "holderType")
-
         declType = CGGeneric(type.name + "::" + type.name)
         if type.nullable():
             declType = CGWrapper(declType, pre="Option<", post=" >")
diff --git a/src/components/script/dom/testbinding.rs b/src/components/script/dom/testbinding.rs
index dd439a1622a..4f0a2081bf7 100644
--- a/src/components/script/dom/testbinding.rs
+++ b/src/components/script/dom/testbinding.rs
@@ -255,6 +255,26 @@ pub trait TestBindingMethods {
     // fn PassOptionalNullableDoubleWithNonNullDefault(&self, _: Option<f64>) {}
     fn PassOptionalNullableStringWithNonNullDefault(&self, _: Option<DOMString>) {}
     // fn PassOptionalNullableEnumWithNonNullDefault(&self, _: Option<TestEnum>) {}
+
+    fn PassVariadicBoolean(&self, _: Vec<bool>) {}
+    fn PassVariadicByte(&self, _: Vec<i8>) {}
+    fn PassVariadicOctet(&self, _: Vec<u8>) {}
+    fn PassVariadicShort(&self, _: Vec<i16>) {}
+    fn PassVariadicUnsignedShort(&self, _: Vec<u16>) {}
+    fn PassVariadicLong(&self, _: Vec<i32>) {}
+    fn PassVariadicUnsignedLong(&self, _: Vec<u32>) {}
+    fn PassVariadicLongLong(&self, _: Vec<i64>) {}
+    fn PassVariadicUnsignedLongLong(&self, _: Vec<u64>) {}
+    fn PassVariadicFloat(&self, _: Vec<f32>) {}
+    fn PassVariadicDouble(&self, _: Vec<f64>) {}
+    fn PassVariadicString(&self, _: Vec<DOMString>) {}
+    fn PassVariadicByteString(&self, _: Vec<ByteString>) {}
+    fn PassVariadicEnum(&self, _: Vec<TestEnum>) {}
+    // fn PassVariadicInterface(&self, _: Vec<JSRef<Blob>>) {}
+    fn PassVariadicUnion(&self, _: Vec<HTMLElementOrLong>) {}
+    fn PassVariadicUnion2(&self, _: Vec<EventOrString>) {}
+    fn PassVariadicUnion3(&self, _: Vec<BlobOrString>) {}
+    fn PassVariadicAny(&self, _: *mut JSContext, _: Vec<JSVal>) {}
 }
 
 impl<'a> TestBindingMethods for JSRef<'a, TestBinding> {
diff --git a/src/components/script/dom/webidls/TestBinding.webidl b/src/components/script/dom/webidls/TestBinding.webidl
index 6d2137cdd60..2437514a2c1 100644
--- a/src/components/script/dom/webidls/TestBinding.webidl
+++ b/src/components/script/dom/webidls/TestBinding.webidl
@@ -246,4 +246,24 @@ interface TestBinding {
   // void passOptionalNullableEnumWithNonNullDefault(optional TestEnum? arg = "foo");
   // void passOptionalNullableUnionWithNonNullDefault(optional (HTMLElement or long)? arg = 7);
   // void passOptionalNullableUnion2WithNonNullDefault(optional (Event or DOMString)? data = "foo");
+
+  void passVariadicBoolean(boolean... args);
+  void passVariadicByte(byte... args);
+  void passVariadicOctet(octet... args);
+  void passVariadicShort(short... args);
+  void passVariadicUnsignedShort(unsigned short... args);
+  void passVariadicLong(long... args);
+  void passVariadicUnsignedLong(unsigned long... args);
+  void passVariadicLongLong(long long... args);
+  void passVariadicUnsignedLongLong(unsigned long long... args);
+  void passVariadicFloat(float... args);
+  void passVariadicDouble(double... args);
+  void passVariadicString(DOMString... args);
+  void passVariadicByteString(ByteString... args);
+  void passVariadicEnum(TestEnum... args);
+  // void passVariadicInterface(Blob... args);
+  void passVariadicUnion((HTMLElement or long)... args);
+  void passVariadicUnion2((Event or DOMString)... args);
+  void passVariadicUnion3((Blob or DOMString)... args);
+  void passVariadicAny(any... args);
 };