Replaced PassRefPtr copies with moves in Source/core.

third_party/WebKit/Source/core/frame/DOMWindow.cpp

Index: third_party/WebKit/Source/core/frame/DOMWindow.cpp
diff --git a/third_party/WebKit/Source/core/frame/DOMWindow.cpp b/third_party/WebKit/Source/core/frame/DOMWindow.cpp
index 3d1f12c7efdbb84f6907c18c4ecbfee3775d98b8..1282cf0a7dff3b509cba3ad7099110078f0a29b0 100644
--- a/third_party/WebKit/Source/core/frame/DOMWindow.cpp
+++ b/third_party/WebKit/Source/core/frame/DOMWindow.cpp
@@ -227,7 +227,7 @@ void DOMWindow::postMessage(PassRefPtr<SerializedScriptValue> message, const Mes
     else if (MixedContentChecker::isMixedContent(frame()->securityContext()->getSecurityOrigin(), sourceDocument->url()))
         UseCounter::count(frame(), UseCounter::PostMessageFromInsecureToSecure);
 
-    MessageEvent* event = MessageEvent::create(std::move(channels), message, sourceOrigin, String(), source, sourceSuborigin);
+    MessageEvent* event = MessageEvent::create(std::move(channels), std::move(message), sourceOrigin, String(), source, sourceSuborigin);
 
     schedulePostMessage(event, std::move(target), sourceDocument);
 }