Remove ResourceFetcher's access to a real FetchContext at frame detach time

Source/core/html/imports/LinkImport.cpp

Index: Source/core/html/imports/LinkImport.cpp
diff --git a/Source/core/html/imports/LinkImport.cpp b/Source/core/html/imports/LinkImport.cpp
index 3a3e629e9812eac13882fd23e80eef820c7b98d6..812afedd10b4957c7cb9b20f74cf66d926e118f6 100644
--- a/Source/core/html/imports/LinkImport.cpp
+++ b/Source/core/html/imports/LinkImport.cpp
@@ -128,9 +128,7 @@ HTMLLinkElement* LinkImport::link()
 
 bool LinkImport::hasLoaded() const
 {
-    // Should never be called after importChildWasDestroyed was called.
-    ASSERT(m_owner);
-    return m_child && m_child->hasFinishedLoading() && !m_child->loader()->hasError();
+    return m_owner && m_child && m_child->hasFinishedLoading() && !m_child->loader()->hasError();
 }
 
 void LinkImport::ownerInserted()