Simplify and add caching for accessible bounding box calculation.

Source/core/accessibility/AccessibilityObject.h

Index: Source/core/accessibility/AccessibilityObject.h
diff --git a/Source/core/accessibility/AccessibilityObject.h b/Source/core/accessibility/AccessibilityObject.h
index 91edb7de5d6ed7f26ec0635bb57397115559641c..fcf93b552bec9e69e3d4c684057468e238df5603 100644
--- a/Source/core/accessibility/AccessibilityObject.h
+++ b/Source/core/accessibility/AccessibilityObject.h
@@ -425,7 +425,7 @@ public:
     // 1-based, to match the aria-level spec.
     virtual unsigned hierarchicalLevel() const { return 0; }
     virtual void linkedUIElements(AccessibilityChildrenVector&) const { }
-    virtual AccessibilityOrientation orientation() const;
+    virtual AccessibilityOrientation orientation();
     virtual void tabChildren(AccessibilityChildrenVector&) { }
     virtual int tableLevel() const { return 0; }
     virtual String text() const { return String(); }
@@ -503,21 +503,17 @@ public:
     virtual String title() const { return String(); }
     virtual String helpText() const { return String(); }
 
-    // Position and size.
-    virtual LayoutRect boundingBoxRect() const { return LayoutRect(); }
-    IntRect pixelSnappedBoundingBoxRect() const { return pixelSnappedIntRect(boundingBoxRect()); }
-    virtual LayoutRect elementRect() const = 0;
-    IntRect pixelSnappedElementRect() const { return pixelSnappedIntRect(elementRect()); }
-    LayoutSize size() const { return elementRect().size(); }
-    IntSize pixelSnappedSize() const { return elementRect().pixelSnappedSize(); }
+    // Location and click point in frame-relative coordinates.
+    virtual LayoutRect elementRect() { return LayoutRect(); }
+    virtual void updateCachedElementRect() { }
+    virtual void markCachedElementRectDirty();
     virtual IntPoint clickPoint();
-    static IntRect boundingBoxForQuads(RenderObject*, const Vector<FloatQuad>&);
 
     // Hit testing.
     // Called on the root AX object to return the deepest available element.
     virtual AccessibilityObject* accessibilityHitTest(const IntPoint&) const { return 0; }
     // Called on the AX object after the render tree determines which is the right AccessibilityRenderObject.
-    virtual AccessibilityObject* elementAccessibilityHitTest(const IntPoint&) const;
+    virtual AccessibilityObject* elementAccessibilityHitTest(const IntPoint&);
 
     // High-level accessibility tree access. Other modules should only use these functions.
     const AccessibilityChildrenVector& children();
@@ -577,11 +573,11 @@ public:
     virtual bool performDefaultAction() const { return press(); }
     virtual bool press() const;
     // Make this object visible by scrolling as many nested scrollable views as needed.
-    virtual void scrollToMakeVisible() const;
+    virtual void scrollToMakeVisible();
     // Same, but if the whole object can't be made visible, try for this subrect, in local coordinates.
-    virtual void scrollToMakeVisibleWithSubFocus(const IntRect&) const;
+    virtual void scrollToMakeVisibleWithSubFocus(const IntRect&);
     // Scroll this object to a given point in global coordinates of the top-level window.
-    virtual void scrollToGlobalPoint(const IntPoint&) const;
+    virtual void scrollToGlobalPoint(const IntPoint&);
     virtual void setAccessibleName(const AtomicString&) { }
     virtual void setFocused(bool) { }
     virtual void setSelected(bool) { }
@@ -674,6 +670,7 @@ public:
     static bool isARIAInput(AccessibilityRole);
     static AccessibilityObject* anchorElementForNode(Node*);
     static AccessibilityRole ariaRoleToWebCoreRole(const String&);
+    static IntRect boundingBoxForQuads(RenderObject*, const Vector<FloatQuad>&);
 
 protected:
     AXID m_id;