Bug 1439223: Stop ShadowRoot::Host from being a useless function call. r=smaug

Also, change DocumentFragment to use RefPtr, since that's the usual style.

MozReview-Commit-ID: 4PQ19nbmhUh

--HG--
extra : rebase_source : 2afb214b764ba48a4a8718190a6853ae6d6ea80b

dom/base/DocumentFragment.h

@@ -107,7 +107,7 @@ protected:
 
   nsresult Clone(mozilla::dom::NodeInfo *aNodeInfo, nsINode **aResult,
                  bool aPreallocateChildren) const override;
-  nsCOMPtr<Element> mHost;
+  RefPtr<Element> mHost;
 };
 
 } // namespace dom

dom/base/ShadowRoot.cpp

@@ -450,16 +450,6 @@ ShadowRoot::SetInnerHTML(const nsAString& aInnerHTML, ErrorResult& aError)
   SetInnerHTMLInternal(aInnerHTML, aError);
 }
 
-Element*
-ShadowRoot::Host()
-{
-  nsIContent* host = GetHost();
-  MOZ_ASSERT(host && host->IsElement(),
-             "ShadowRoot host should always be an element, "
-             "how else did we create this ShadowRoot?");
-  return host->AsElement();
-}
-
 void
 ShadowRoot::AttributeChanged(nsIDocument* aDocument,
                              Element* aElement,

dom/base/ShadowRoot.h

@@ -65,7 +65,13 @@ public:
              nsXBLPrototypeBinding* aProtoBinding);
 
   // Shadow DOM v1
-  Element* Host();
+  Element* Host() const
+  {
+    MOZ_ASSERT(GetHost(), "ShadowRoot always has a host, how did we create "
+                          "this ShadowRoot?");
+    return GetHost();
+  }
+
   ShadowRootMode Mode() const
   {
     return mMode;