[SVG] Implement 'discard' element

Source/core/svg/animation/SMILTimeContainer.cpp

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 #include "config.h"
 #include "core/svg/animation/SMILTimeContainer.h"
 
 #include "core/dom/ElementTraversal.h"
+#include "core/svg/SVGDiscardElement.h"
 #include "core/svg/SVGSVGElement.h"
 #include "core/svg/animation/SVGSMILElement.h"
 #include "wtf/CurrentTime.h"
 
 using namespace std;
 
 namespace WebCore {
 
 static const double animationFrameDelay = 0.025;
 
@@ skipping 222 matching lines @@
 void SMILTimeContainer::updateAnimations(SMILTime elapsed, bool seekToTime)
 {
     SMILTime earliestFireTime = SMILTime::unresolved();
 
 #ifndef NDEBUG
     // This boolean will catch any attempts to schedule/unschedule scheduledAnimations during this critical section.
     // Similarly, any elements removed will unschedule themselves, so this will catch modification of animationsToApply.
     m_preventScheduledAnimationsChanges = true;
 #endif
 
-    AnimationsVector animationsToApply;
+    Vector< RefPtr<SVGSMILElement> >  animationsToApply;
     GroupedAnimationsMap::iterator end = m_scheduledAnimations.end();
     for (GroupedAnimationsMap::iterator it = m_scheduledAnimations.begin(); it != end; ++it) {
         AnimationsVector* scheduled = it->value.get();
 
         // Sort according to priority. Elements with later begin time have higher priority.
         // In case of a tie, document order decides.
         // FIXME: This should also consider timing relationships between the elements. Dependents
         // have higher priority.
         sortByPriority(*scheduled, elapsed);
 
@@ skipping 35 matching lines @@
     }
 
     // Apply results to target elements.
     for (unsigned i = 0; i < animationsToApplySize; ++i)
         animationsToApply[i]->applyResultsToTarget();
 
 #ifndef NDEBUG
     m_preventScheduledAnimationsChanges = false;
 #endif
 
+    for (unsigned n = 0; n < animationsToApplySize; ++n) {
+        if (animationsToApply[n] && animationsToApply[n]->inDocument() && isSVGDiscardElement(*animationsToApply[n])) {

[pdr., 2013/12/20 23:49:11]

Can animationsToApply[n] ever be null? I don't think that it can, so you can
remove the animationsToApply[n] check.

+            RefPtr<SVGSMILElement> animDiscard = animationsToApply[n];
+            RefPtr<SVGElement> targetElement = animDiscard->targetElement();
+            animDiscard->remove(IGNORE_EXCEPTION);

[pdr., 2013/12/20 23:49:11]

I think the ordering here matters. Can you remove the target first, then the
discard?

[pavane, 2013/12/21 12:28:10]

I think the current order is logical. If discard is a child of the target, then
it is better to remove the child first and then the parent. It will avoid us
another inDocument() check.

+            if (targetElement && targetElement->inDocument())
+                targetElement->remove(IGNORE_EXCEPTION);

[pdr., 2013/12/20 23:49:11]

After both of these removal calls, can you add:
ASSERT(!element->inDocument())?

+        }
+    }
+
     startTimer(earliestFireTime, animationFrameDelay);
 }
 
 }