[bindings] Club related constants for a runtime enabled flag in a single |if| block

Source/bindings/tests/idls/core/TestPartialInterface.idl

 /*
  * Copyright (C) 2014 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions are
  * met:
  *
  *     * Redistributions of source code must retain the above copyright
  * notice, this list of conditions and the following disclaimer.
  *     * Redistributions in binary form must reproduce the above
@@ skipping 23 matching lines @@
 };
 
 typedef DOMString PartialString;
 
 callback PartialCallbackType = void (PartialString value);
 [
     Conditional=PARTIAL_CONDITION,
     RuntimeEnabled=PartialFeatureName,
 ] partial interface TestInterface {
     const unsigned short PARTIAL_UNSIGNED_SHORT = 0;
+    const double PARTIAL_DOUBLE = 3.14;
 
     attribute long partialLongAttribute;
     static attribute long partialStaticLongAttribute;
     [CallWith=ExecutionContext] attribute long partialCallWithExecutionContextLongAttribute;
 
     void partialVoidMethod();
     static void partialStaticVoidMethod();
     void partialVoidMethodLongArg(long longArg);
     [CallWith=ExecutionContext, RaisesException] void partialCallWithExecutionContextRaisesExceptionVoidMethod();
 
     attribute PartialEnumType partialPartialEnumTypeAttribute;
     void partialVoidMethodPartialCallbackTypeArg(PartialCallbackType partialCallbackTypeArg);
 
     [ImplementedInPrivateScript] short shortMethodWithShortArgumentImplementedInPrivateScript(short value);
     [ImplementedInPrivateScript] attribute DOMString stringAttribute;
 };