The DOMRectReadOnly interface requires serializer.

third_party/WebKit/Source/core/dom/DOMRectReadOnly.h

Index: third_party/WebKit/Source/core/dom/DOMRectReadOnly.h
diff --git a/third_party/WebKit/Source/core/dom/DOMRectReadOnly.h b/third_party/WebKit/Source/core/dom/DOMRectReadOnly.h
index a15f7869dd87ada616f10dd33440d962cf341028..1a14e25499adaf9440660adb4b30c660f3ce50f2 100644
--- a/third_party/WebKit/Source/core/dom/DOMRectReadOnly.h
+++ b/third_party/WebKit/Source/core/dom/DOMRectReadOnly.h
@@ -11,6 +11,9 @@
 
 namespace blink {
 
+class ScriptValue;
+class ScriptState;
+
 class CORE_EXPORT DOMRectReadOnly : public GarbageCollected<DOMRectReadOnly>,
                                     public ScriptWrappable {
   DEFINE_WRAPPERTYPEINFO();
@@ -33,6 +36,8 @@ class CORE_EXPORT DOMRectReadOnly : public GarbageCollected<DOMRectReadOnly>,
 
   DEFINE_INLINE_TRACE() {}
 
+  ScriptValue toJSONForBinding(ScriptState*) const;
+
  protected:
   DOMRectReadOnly(double x, double y, double width, double height);