Remove "legacy" experimental stream support

third_party/WebKit/Source/core/xmlhttprequest/XMLHttpRequest.idl

 /*
  * Copyright (C) 2008, 2011 Apple 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:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
  * 2.  Redistributions in binary form must reproduce the above copyright
@@ skipping 17 matching lines @@
 
 // https://xhr.spec.whatwg.org/#interface-xmlhttprequest
 
 enum XMLHttpRequestResponseType {
     "",
     "arraybuffer",
     "blob",
     "document",
     "json",
     "text",
-    "legacystream",
 };
 
 // TODO(foolip): Most DOMString types in the XMLHttpRequest interface should be
 // either ByteString or USVString.
 [
     ActiveScriptWrappable,
     Constructor,
     ConstructorCallWith=ScriptState,
     DependentLifetime,
     Exposed=(Window,DedicatedWorker,SharedWorker),
@@ skipping 27 matching lines @@
     readonly attribute DOMString statusText;
     DOMString? getResponseHeader(DOMString name);
     DOMString getAllResponseHeaders();
     [RaisesException] void overrideMimeType(DOMString mime);
     [RaisesException=Setter] attribute XMLHttpRequestResponseType responseType;
     [Custom=Getter, RaisesException=Getter] readonly attribute any response;
     [Custom=Getter, RaisesException=Getter] readonly attribute DOMString responseText;
     // TODO(foolip): responseXML should be [Exposed=Window].
     [RaisesException=Getter] readonly attribute Document? responseXML;
 };