Simply SVGSVGElement::getElementById method

Source/core/svg/SVGSVGElement.cpp

Index: Source/core/svg/SVGSVGElement.cpp
diff --git a/Source/core/svg/SVGSVGElement.cpp b/Source/core/svg/SVGSVGElement.cpp
index 30cf7fa27e2e365a56436721ca0275a31bc85b6a..c175f07450587cf151bbca14dfe248ac3af957d2 100644
--- a/Source/core/svg/SVGSVGElement.cpp
+++ b/Source/core/svg/SVGSVGElement.cpp
@@ -767,20 +767,22 @@ void SVGSVGElement::inheritViewAttributes(SVGViewElement* viewElement)
 // See http://www.w3.org/TR/SVG11/struct.html#InterfaceSVGSVGElement
 Element* SVGSVGElement::getElementById(const AtomicString& id) const
 {
-    Element* element = treeScope().getElementById(id);
-    if (element && element->isDescendantOf(this))
-        return element;
+    if (!treeScope().containsMultipleElementsWithId(id)) {
+        Element* element = treeScope().getElementById(id);

[f(malita), 2014/02/24 23:47:24]

Isn't this introducing an extra lookup for the common case?

(one for containsMultipleElementsWithId() and another one for getElementById())

Whereas before, the fast path only took one lookup: getElementById().

+        if (!element || !element->isDescendantOf(this))
+            return 0;
 
-    // Fall back to traversing our subtree. Duplicate ids are allowed, the first found will
-    // be returned.
-    for (Node* node = firstChild(); node; node = NodeTraversal::next(*node, this)) {
-        if (!node->isElementNode())
-            continue;
+        return element;
+    }
 
-        Element* element = toElement(node);
-        if (element->getIdAttribute() == id)
-            return element;
+    // If duplicate IDs are there, return the first descendant of the svg element.
+    const Vector<Element*>& elements = treeScope().getAllElementsById(id);
+    Vector<Element*>::const_iterator end = elements.end();
+    for (Vector<Element*>::const_iterator it = elements.begin(); it != end; ++it) {
+        if ((*it)->isDescendantOf(this))
+            return *it;
     }
+
     return 0;
 }