Bug 933193 part 2. Implement nsINode::GetElementById and make SVGSVGElement use it. r=smaug

content/base/public/nsINode.h

@@ -1076,6 +1076,12 @@ public:
   nsresult QuerySelector(const nsAString& aSelector, nsIDOMElement **aReturn);
   nsresult QuerySelectorAll(const nsAString& aSelector, nsIDOMNodeList **aReturn);
 
+protected:
+  // nsIDocument overrides this with its own (faster) version.  This
+  // should really only be called for elements and document fragments.
+  mozilla::dom::Element* GetElementById(const nsAString& aId);
+
+public:
   /**
    * Associate an object aData to aKey on this node. If aData is null any
    * previously registered object and UserDataHandler associated to aKey on

content/base/src/nsINode.cpp

@@ -2519,6 +2519,29 @@ nsINode::QuerySelectorAll(const nsAString& aSelector, nsIDOMNodeList **aReturn)
   return rv.ErrorCode();
 }
 
+Element*
+nsINode::GetElementById(const nsAString& aId)
+{
+  MOZ_ASSERT(IsElement() || IsNodeOfType(eDOCUMENT_FRAGMENT),
+             "Bogus this object for GetElementById call");
+  if (IsInDoc()) {
+    ElementHolder holder;
+    FindMatchingElementsWithId<true>(aId, this, nullptr, holder);
+    return holder.mElement;
+  }
+
+  for (nsIContent* kid = GetFirstChild(); kid; kid = kid->GetNextNode(this)) {
+    if (!kid->IsElement()) {
+      continue;
+    }
+    nsIAtom* id = kid->AsElement()->GetID();
+    if (id && id->Equals(aId)) {
+      return kid->AsElement();
+    }
+  }
+  return nullptr;
+}
+
 JSObject*
 nsINode::WrapObject(JSContext *aCx, JS::Handle<JSObject*> aScope)
 {

content/svg/content/src/SVGSVGElement.cpp

@@ -435,18 +435,6 @@ SVGSVGElement::CreateSVGTransformFromMatrix(SVGMatrix& matrix)
   return transform.forget();
 }
 
-Element*
-SVGSVGElement::GetElementById(const nsAString& elementId, ErrorResult& rv)
-{
-  nsAutoString selector(NS_LITERAL_STRING("#"));
-  nsStyleUtil::AppendEscapedCSSIdent(PromiseFlatString(elementId), selector);
-  nsIContent* element = QuerySelector(selector, rv);
-  if (!rv.Failed() && element) {
-    return element->AsElement();
-  }
-  return nullptr;
-}
-
 //----------------------------------------------------------------------
 
 already_AddRefed<SVGAnimatedRect>

content/svg/content/src/SVGSVGElement.h

@@ -246,7 +246,7 @@ public:
   already_AddRefed<SVGIRect> CreateSVGRect();
   already_AddRefed<SVGTransform> CreateSVGTransform();
   already_AddRefed<SVGTransform> CreateSVGTransformFromMatrix(SVGMatrix& matrix);
-  Element* GetElementById(const nsAString& elementId, ErrorResult& rv);
+  using nsINode::GetElementById; // This does what we want
   already_AddRefed<SVGAnimatedRect> ViewBox();
   already_AddRefed<DOMSVGAnimatedPreserveAspectRatio> PreserveAspectRatio();
   uint16_t ZoomAndPan();

dom/webidl/SVGSVGElement.webidl

@@ -59,7 +59,6 @@ interface SVGSVGElement : SVGGraphicsElement {
   SVGTransform createSVGTransform();
   [NewObject]
   SVGTransform createSVGTransformFromMatrix(SVGMatrix matrix);
-  [Throws]
   Element? getElementById(DOMString elementId);
 };