Build fix when SERVICE_WORKER is disabled

https://bugs.webkit.org/show_bug.cgi?id=264902

Reviewed by Don Olmstead.

When SERVICE_WORKER is dsabled, building webkit fails.
Functions below in GeneratedSerializers.cpp should be disabled when SERVICE_WORKER is off.

isValidEnum<WebCore::BackgroundFetchFailureReason, void>
isValidEnum<WebCore::BackgroundFetchResult, void>

* Source/WebKit/Shared/WebCoreArgumentCoders.serialization.in:

Canonical link: https://commits.webkit.org/270920@main

Source/WebKit/Shared/WebCoreArgumentCoders.serialization.in

@@ -6664,6 +6664,7 @@ enum class WebCore::ExceptionCode : uint8_t {
     ExistingExceptionError,
 }
 
+#if ENABLE(SERVICE_WORKER)
 header: <WebCore/BackgroundFetchFailureReason.h>
 enum class WebCore::BackgroundFetchFailureReason : uint8_t {
     EmptyString,
@@ -6673,13 +6674,16 @@ enum class WebCore::BackgroundFetchFailureReason : uint8_t {
     QuotaExceeded,
     DownloadTotalExceeded
 };
+#endif
 
+#if ENABLE(SERVICE_WORKER)
 header: <WebCore/BackgroundFetchResult.h>
 enum class WebCore::BackgroundFetchResult : uint8_t {
     EmptyString,
     Success,
     Failure
 };
+#endif
 
 enum class WebCore::ResourceErrorBaseType : uint8_t {
      Null,