The DOMRectReadOnly interface requires serializer.

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

Index: third_party/WebKit/Source/core/dom/DOMRectReadOnly.cpp
diff --git a/third_party/WebKit/Source/core/dom/DOMRectReadOnly.cpp b/third_party/WebKit/Source/core/dom/DOMRectReadOnly.cpp
index 54dac6e0c8544b91e3e815d08ad3f807265f808a..3b09920df6ed806de5715b72aeff6ee9a89f1750 100644
--- a/third_party/WebKit/Source/core/dom/DOMRectReadOnly.cpp
+++ b/third_party/WebKit/Source/core/dom/DOMRectReadOnly.cpp
@@ -4,6 +4,9 @@
 
 #include "core/dom/DOMRectReadOnly.h"
 
+#include "bindings/core/v8/ScriptValue.h"
+#include "bindings/core/v8/V8ObjectBuilder.h"
+
 namespace blink {
 
 DOMRectReadOnly* DOMRectReadOnly::create(double x,
@@ -13,6 +16,19 @@ DOMRectReadOnly* DOMRectReadOnly::create(double x,
   return new DOMRectReadOnly(x, y, width, height);
 }
 
+ScriptValue DOMRectReadOnly::toJSONForBinding(ScriptState* scriptState) const {
+  V8ObjectBuilder result(scriptState);
+  result.addNumber("x", x());
+  result.addNumber("y", y());
+  result.addNumber("width", width());
+  result.addNumber("height", height());
+  result.addNumber("top", top());
+  result.addNumber("right", right());
+  result.addNumber("bottom", bottom());
+  result.addNumber("left", left());
+  return result.scriptValue();
+}
+
 DOMRectReadOnly::DOMRectReadOnly(double x,
                                  double y,
                                  double width,