Split Dictionary's get and convert into DictionaryHelper.

Source/modules/serviceworkers/RequestInit.h

Index: Source/modules/serviceworkers/RequestInit.h
diff --git a/Source/modules/serviceworkers/RequestInit.h b/Source/modules/serviceworkers/RequestInit.h
index f8bad76b4059830a77b16bcef8a591ece01872c0..fbd31fde6769c38dbc451a7e5b3f711dca654426 100644
--- a/Source/modules/serviceworkers/RequestInit.h
+++ b/Source/modules/serviceworkers/RequestInit.h
@@ -6,6 +6,7 @@
 #define RequestInit_h
 
 #include "bindings/core/v8/Dictionary.h"
+#include "bindings/core/v8/DictionaryHelper.h"
 #include "modules/serviceworkers/Headers.h"
 #include "wtf/RefPtr.h"
 
@@ -14,13 +15,13 @@ namespace WebCore {
 struct RequestInit {
     explicit RequestInit(const Dictionary& options)
     {
-        options.get("method", method);
-        options.get("headers", headers);
+        DictionaryHelper::get(options, "method", method);
+        DictionaryHelper::get(options, "headers", headers);
         if (!headers) {
-            options.get("headers", headersDictionary);
+            DictionaryHelper::get(options, "headers", headersDictionary);
         }
-        options.get("mode", mode);
-        options.get("credentials", credentials);
+        DictionaryHelper::get(options, "mode", mode);
+        DictionaryHelper::get(options, "credentials", credentials);
     }
 
     String method;