Support 'Conditional' idl attribute.

client/dom/generated/src/frog/InjectedScriptHost.dart

-
-class _InjectedScriptHostJs extends _DOMTypeJs implements InjectedScriptHost native "*InjectedScriptHost" {
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-  void clearConsoleMessages() native;
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-  void copyText(String text) native;
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-  int databaseId(Object database) native;
-
-  void didCreateWorker(int id, String url, bool isFakeWorker) native;
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-  void didDestroyWorker(int id) native;
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-  Object evaluate(String text) native;
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-  Object functionDetails(Object object) native;
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-  void inspect(Object objectId, Object hints) native;
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-  Object inspectedNode(int num) native;
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-  Object internalConstructorName(Object object) native;
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-  bool isHTMLAllCollection(Object object) native;
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-  int nextWorkerId() native;
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-  int storageId(Object storage) native;
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-  String type(Object object) native;
-}