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

Source/core/dom/Document.cpp

Index: Source/core/dom/Document.cpp
diff --git a/Source/core/dom/Document.cpp b/Source/core/dom/Document.cpp
index aedb82cfd8d8e76b27f94995805b7fa7464715f8..e96a85bd55620ebf358c09ed5da5e61253deed3c 100644
--- a/Source/core/dom/Document.cpp
+++ b/Source/core/dom/Document.cpp
@@ -821,7 +821,7 @@ void Document::setImportsController(HTMLImportsController* controller)
 {
     ASSERT(!m_importsController || !controller);
     m_importsController = controller;
-    if (!m_importsController && !loader())
+    if (!m_importsController && !loader() && m_fetcher)
         m_fetcher->clearContext();
 }
 
@@ -2205,7 +2205,7 @@ void Document::detach(const AttachContext& context)
     // to the DocumentLoader when possible also prevents prematurely clearing
     // the context in the case where multiple Documents end up associated with
     // a single DocumentLoader (e.g., navigating to a javascript: url).
-    if (!loader())
+    if (!loader() && m_fetcher)
         m_fetcher->clearContext();
     // If this document is the master for an HTMLImportsController, sever that
     // relationship. This ensures that we don't leave import loads in flight,
@@ -2234,6 +2234,8 @@ void Document::detach(const AttachContext& context)
     // created by DOMImplementation::createDocument().
     DocumentLifecycleNotifier::notifyContextDestroyed();
     ExecutionContext::notifyContextDestroyed();
+
+    m_fetcher.clear();
 }
 
 void Document::removeAllEventListeners()
@@ -4636,7 +4638,8 @@ void Document::finishedParsing()
     m_elementDataCacheClearTimer.startOneShot(10, FROM_HERE);
 
     // Parser should have picked up all preloads by now
-    m_fetcher->clearPreloads();
+    if (m_fetcher)
+        m_fetcher->clearPreloads();
 }
 
 void Document::elementDataCacheClearTimerFired(Timer<Document>*)