Allow origin trials to be declared on IDL operations (methods)

third_party/WebKit/Source/bindings/tests/idls/modules/TestInterfacePartial4.idl

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Test for [OriginTrialEnabled] extended attribute applied to a partial
 // interface. This is separate from TestInterfacePartial, as the 
 // [OriginTrialEnabled] attribute cannot be applied with [RuntimeEnabled].
 
 [
     OriginTrialEnabled=OriginTrialPartialFeature, // Conflicts with RuntimeEnabled
 ] partial interface TestInterface {
     const unsigned short PARTIAL4_UNSIGNED_SHORT = 4;
 
     attribute long partial4LongAttribute;
     // TODO(chasej): Uncomment when static attributes are supported for origin trials (crbug.com/614352)
     //static attribute long partial4StaticLongAttribute;
 
     // TODO(chasej): Uncomment when methods are supported for origin trials (crbug.com/621641)
-    //void partial4VoidMethod();
+    void partial4VoidMethod();
     //static void partial4StaticVoidMethod();
 };