--- a/dom/html/HTMLAnchorElement.cpp
+++ b/dom/html/HTMLAnchorElement.cpp
@@ -9,16 +9,17 @@
 #include "mozilla/dom/HTMLAnchorElementBinding.h"
 #include "mozilla/EventDispatcher.h"
 #include "mozilla/EventStates.h"
 #include "mozilla/MemoryReporting.h"
 #include "nsCOMPtr.h"
 #include "nsContentUtils.h"
 #include "nsGkAtoms.h"
 #include "nsHTMLDNSPrefetch.h"
+#include "nsAttrValueOrString.h"
 #include "nsIDocument.h"
 #include "nsIPresShell.h"
 #include "nsPresContext.h"
 #include "nsIURI.h"
 
 NS_IMPL_NS_NEW_HTML_ELEMENT(Anchor)
 
 namespace mozilla {
@@ -360,94 +361,75 @@ HTMLAnchorElement::GetHrefURI() const
   if (uri) {
     return uri.forget();
   }
 
   return GetHrefURIForAnchors();
 }
 
 nsresult
-HTMLAnchorElement::SetAttr(int32_t aNameSpaceID, nsIAtom* aName,
-                           nsIAtom* aPrefix, const nsAString& aValue,
-                           bool aNotify)
+HTMLAnchorElement::BeforeSetAttr(int32_t aNamespaceID, nsIAtom* aName,
+                                 const nsAttrValueOrString* aValue,
+                                 bool aNotify)
 {
-  bool reset = false;
-  if (aName == nsGkAtoms::href && kNameSpaceID_None == aNameSpaceID) {
-    // If we do not have a cached URI, we have some value here so we must reset
-    // our link state after calling the parent.
-    if (!Link::HasCachedURI()) {
-      reset = true;
-    }
-    // However, if we have a cached URI, we'll want to see if the value changed.
-    else {
-      nsAutoString val;
-      GetHref(val);
-      if (!val.Equals(aValue)) {
+  if (aNamespaceID == kNameSpaceID_None) {
+    if (aName == nsGkAtoms::href) {
+      bool reset = false;
+      if (!aValue) {
         reset = true;
+      } else {
+        // If we do not have a cached URI, we have some value here so we must
+        // reset our link state after calling the parent.
+        if (!Link::HasCachedURI()) {
+          reset = true;
+        }
+        // However, if we have a cached URI, we'll want to see if the value
+        // changed.
+        else {
+          const nsAttrValue* oldValue =
+            mAttrsAndChildren.GetAttr(nsGkAtoms::href);
+          if (!aValue->EqualsAsStrings(*oldValue)) {
+            reset = true;
+          }
+        }
       }
-    }
-    if (reset) {
-      CancelDNSPrefetch(HTML_ANCHOR_DNS_PREFETCH_DEFERRED,
-                        HTML_ANCHOR_DNS_PREFETCH_REQUESTED);
+      if (reset) {
+        CancelDNSPrefetch(HTML_ANCHOR_DNS_PREFETCH_DEFERRED,
+                          HTML_ANCHOR_DNS_PREFETCH_REQUESTED);
+      }
     }
   }
 
-  nsresult rv = nsGenericHTMLElement::SetAttr(aNameSpaceID, aName, aPrefix,
-                                              aValue, aNotify);
-
-  // The ordering of the parent class's SetAttr call and Link::ResetLinkState
-  // is important here!  The attribute is not set until SetAttr returns, and
-  // we will need the updated attribute value because notifying the document
-  // that content states have changed will call IntrinsicState, which will try
-  // to get updated information about the visitedness from Link.
-  if (reset) {
-    Link::ResetLinkState(!!aNotify, true);
-    if (IsInComposedDoc()) {
-      TryDNSPrefetch();
-    }
-  }
-
-  return rv;
+  return nsGenericHTMLElement::BeforeSetAttr(aNamespaceID, aName, aValue,
+                                             aNotify);
 }
 
 nsresult
-HTMLAnchorElement::UnsetAttr(int32_t aNameSpaceID, nsIAtom* aAttribute,
-                             bool aNotify)
+HTMLAnchorElement::AfterSetAttr(int32_t aNamespaceID, nsIAtom* aName,
+                                const nsAttrValue* aValue,
+                                const nsAttrValue* aOldValue, bool aNotify)
 {
-  bool href =
-    (aAttribute == nsGkAtoms::href && kNameSpaceID_None == aNameSpaceID);
-
-  if (href) {
-    CancelDNSPrefetch(HTML_ANCHOR_DNS_PREFETCH_DEFERRED,
-                      HTML_ANCHOR_DNS_PREFETCH_REQUESTED);
+  if (aNamespaceID == kNameSpaceID_None) {
+    if (aName == nsGkAtoms::href) {
+      if (aValue) {
+        if (!Link::HasCachedURI() || !aOldValue ||
+            !aValue->Equals(*aOldValue)) {
+          Link::ResetLinkState(!!aNotify, true);
+          if (IsInComposedDoc()) {
+            TryDNSPrefetch();
+          }
+        }
+      } else {
+        Link::ResetLinkState(!!aNotify, false);
+      }
+    }
   }
 
-  nsresult rv = nsGenericHTMLElement::UnsetAttr(aNameSpaceID, aAttribute,
-                                                aNotify);
-
-  // The ordering of the parent class's UnsetAttr call and Link::ResetLinkState
-  // is important here!  The attribute is not unset until UnsetAttr returns, and
-  // we will need the updated attribute value because notifying the document
-  // that content states have changed will call IntrinsicState, which will try
-  // to get updated information about the visitedness from Link.
-  if (href) {
-    Link::ResetLinkState(!!aNotify, false);
-  }
-
-  return rv;
-}
-
-bool
-HTMLAnchorElement::ParseAttribute(int32_t aNamespaceID,
-                                  nsIAtom* aAttribute,
-                                  const nsAString& aValue,
-                                  nsAttrValue& aResult)
-{
-  return nsGenericHTMLElement::ParseAttribute(aNamespaceID, aAttribute, aValue,
-                                              aResult);
+  return nsGenericHTMLElement::AfterSetAttr(aNamespaceID, aName,
+                                            aValue, aOldValue, aNotify);
 }
 
 EventStates
 HTMLAnchorElement::IntrinsicState() const
 {
   return Link::LinkState() | nsGenericHTMLElement::IntrinsicState();
 }
 

--- a/dom/html/HTMLAnchorElement.h
+++ b/dom/html/HTMLAnchorElement.h
@@ -61,30 +61,23 @@ public:
   virtual nsresult GetEventTargetParent(
                      EventChainPreVisitor& aVisitor) override;
   virtual nsresult PostHandleEvent(
                      EventChainPostVisitor& aVisitor) override;
   virtual bool IsLink(nsIURI** aURI) const override;
   virtual void GetLinkTarget(nsAString& aTarget) override;
   virtual already_AddRefed<nsIURI> GetHrefURI() const override;
 
-  nsresult SetAttr(int32_t aNameSpaceID, nsIAtom* aName,
-                   const nsAString& aValue, bool aNotify)
-  {
-    return SetAttr(aNameSpaceID, aName, nullptr, aValue, aNotify);
-  }
-  virtual nsresult SetAttr(int32_t aNameSpaceID, nsIAtom* aName,
-                           nsIAtom* aPrefix, const nsAString& aValue,
-                           bool aNotify) override;
-  virtual nsresult UnsetAttr(int32_t aNameSpaceID, nsIAtom* aAttribute,
-                             bool aNotify) override;
-  virtual bool ParseAttribute(int32_t aNamespaceID,
-                                nsIAtom* aAttribute,
-                                const nsAString& aValue,
-                                nsAttrValue& aResult) override;
+  virtual nsresult BeforeSetAttr(int32_t aNamespaceID, nsIAtom* aName,
+                                 const nsAttrValueOrString* aValue,
+                                 bool aNotify) override;
+  virtual nsresult AfterSetAttr(int32_t aNamespaceID, nsIAtom* aName,
+                                const nsAttrValue* aValue,
+                                const nsAttrValue* aOldValue,
+                                bool aNotify) override;
 
   virtual nsresult Clone(mozilla::dom::NodeInfo *aNodeInfo, nsINode **aResult,
                          bool aPreallocateChildren) const override;
 
   virtual EventStates IntrinsicState() const override;
 
   virtual void OnDNSPrefetchDeferred() override;
   virtual void OnDNSPrefetchRequested() override;