[Oilpan] [Reland] Migrate classes under core/fetch to Oilpan heap

Source/core/fetch/FetchContext.cpp

Index: Source/core/fetch/FetchContext.cpp
diff --git a/Source/core/fetch/FetchContext.cpp b/Source/core/fetch/FetchContext.cpp
index d21f070cc718ff058746cea6a9b61af60207158b..af8e54d1d1263d7619123c0169914963ec6ee13c 100644
--- a/Source/core/fetch/FetchContext.cpp
+++ b/Source/core/fetch/FetchContext.cpp
@@ -36,7 +36,7 @@ namespace blink {
 
 FetchContext& FetchContext::nullInstance()
 {
-    DEFINE_STATIC_LOCAL(OwnPtrWillBePersistent<FetchContext>, instance, (adoptPtrWillBeNoop(new FetchContext)));
+    DEFINE_STATIC_LOCAL(Persistent<FetchContext>, instance, (new FetchContext));
     return *instance;
 }