Add Client Attribute to FetchEvent- Blink Side.

Source/modules/serviceworkers/FetchEvent.cpp

Index: Source/modules/serviceworkers/FetchEvent.cpp
diff --git a/Source/modules/serviceworkers/FetchEvent.cpp b/Source/modules/serviceworkers/FetchEvent.cpp
index 81a52fbeb9f5426d73d729afa772aba4394fb085..551c3ffe2f01090d5c6121ccd31aaee2fde73e11 100644
--- a/Source/modules/serviceworkers/FetchEvent.cpp
+++ b/Source/modules/serviceworkers/FetchEvent.cpp
@@ -38,6 +38,11 @@ bool FetchEvent::isReload() const
     return m_isReload;
 }
 
+ServiceWorkerClient* FetchEvent::client() const
+{
+    return m_client;
+}
+
 void FetchEvent::respondWith(ScriptState* scriptState, const ScriptValue& value, ExceptionState& exceptionState)
 {
     stopImmediatePropagation();
@@ -60,6 +65,8 @@ FetchEvent::FetchEvent(const AtomicString& type, const FetchEventInit& initializ
 {
     if (initializer.hasRequest())
         m_request = initializer.request();
+    if (initializer.hasClient())
+        m_client = initializer.client();
     m_isReload = initializer.isReload();
 }