[ServiceWorker] Implement Headers class.

Source/bindings/v8/Dictionary.cpp

Index: Source/bindings/v8/Dictionary.cpp
diff --git a/Source/bindings/v8/Dictionary.cpp b/Source/bindings/v8/Dictionary.cpp
index 77b424e9e6858be8f9f9e710774348cd8b2499af..f7d25e8a54a8eb4e38c0165e89c058192ff76d32 100644
--- a/Source/bindings/v8/Dictionary.cpp
+++ b/Source/bindings/v8/Dictionary.cpp
@@ -37,6 +37,7 @@
 #include "bindings/core/v8/V8Window.h"
 #include "bindings/modules/v8/V8Gamepad.h"
 #include "bindings/modules/v8/V8HeaderMap.h"
+#include "bindings/modules/v8/V8Headers.h"
 #include "bindings/modules/v8/V8IDBKeyRange.h"
 #include "bindings/modules/v8/V8MIDIPort.h"
 #include "bindings/modules/v8/V8MediaStream.h"
@@ -578,6 +579,16 @@ bool Dictionary::get(const String& key, RefPtr<HeaderMap>& value) const
     return true;
 }
 
+bool Dictionary::get(const String& key, RefPtr<Headers>& value) const
+{
+    v8::Local<v8::Value> v8Value;
+    if (!getKey(key, v8Value))
+        return false;
+
+    value = V8Headers::toNativeWithTypeCheck(m_isolate, v8Value);
+    return true;
+}
+
 bool Dictionary::convert(ConversionContext& context, const String& key, Dictionary& value) const
 {
     ConversionContextScope scope(context);