Make some ScriptValue references const

Source/modules/serviceworkers/Headers.cpp

Index: Source/modules/serviceworkers/Headers.cpp
diff --git a/Source/modules/serviceworkers/Headers.cpp b/Source/modules/serviceworkers/Headers.cpp
index 0493a4cd859f4b12aae4263e09e138d5d5cfd2ba..5fca753d7de33e6c1d1c21c482db0d43d1fbf1b2 100644
--- a/Source/modules/serviceworkers/Headers.cpp
+++ b/Source/modules/serviceworkers/Headers.cpp
@@ -210,7 +210,7 @@ void Headers::set(const String& name, const String& value, ExceptionState& excep
     m_headerList->set(name, value);
 }
 
-void Headers::forEach(PassOwnPtr<HeadersForEachCallback> callback, ScriptValue& thisArg)
+void Headers::forEach(PassOwnPtr<HeadersForEachCallback> callback, const ScriptValue& thisArg)
 {
     forEachInternal(callback, &thisArg);
 }
@@ -309,7 +309,7 @@ Headers::Headers(FetchHeaderList* headerList)
     ScriptWrappable::init(this);
 }
 
-void Headers::forEachInternal(PassOwnPtr<HeadersForEachCallback> callback, ScriptValue* thisArg)
+void Headers::forEachInternal(PassOwnPtr<HeadersForEachCallback> callback, const ScriptValue* thisArg)
 {
     TrackExceptionState exceptionState;
     for (size_t i = 0; i < m_headerList->size(); ++i) {