Reset m_didTransformToRootUpdate flag during invalidationTreeIfNeeded

Source/core/rendering/svg/RenderSVGTransformableContainer.h

Index: Source/core/rendering/svg/RenderSVGTransformableContainer.h
diff --git a/Source/core/rendering/svg/RenderSVGTransformableContainer.h b/Source/core/rendering/svg/RenderSVGTransformableContainer.h
index 1103a3b38855a09218788056ebe2450d4350b2cb..dcb086d05a3e8c6fb82b5860a1ad13fbcf09fbc3 100644
--- a/Source/core/rendering/svg/RenderSVGTransformableContainer.h
+++ b/Source/core/rendering/svg/RenderSVGTransformableContainer.h
@@ -35,12 +35,17 @@ public:
     virtual bool isSVGTransformableContainer() const OVERRIDE { return true; }
     virtual const AffineTransform& localToParentTransform() const OVERRIDE { return m_localTransform; }
     virtual void setNeedsTransformUpdate() OVERRIDE { m_needsTransformUpdate = true; }
-    virtual bool didTransformToRootUpdate() OVERRIDE { return m_didTransformToRootUpdate; }
+    virtual bool didTransformToRootUpdate() const OVERRIDE { return m_didTransformToRootUpdate; }

[Julien - ping for review, 2014/07/23 18:47:39]

m_didTransformToRoot is reset during layout (RenderSVGContainer::layout()) so it
seems pretty weird for us to have to do something here.

More conceptually, we may trigger several layouts before producing a frame that
will generate invalidation so it's unclear to me:
A) what this tries to achieve.
B) why this is correct if subsequent layouts could have cleared the flag before
we generate an invalidation.

[Xianzhu, 2014/07/23 18:52:29]

I think you are right. Perhaps we should not clear the flag during layout.

fs@opera.com, wdyt?

[Xianzhu, 2014/07/23 19:05:08]

The latest Patch Set avoids resetting the flag during layout.

+    virtual void clearPaintInvalidationState() OVERRIDE;
 
 private:
     virtual bool calculateLocalTransform() OVERRIDE;
     virtual AffineTransform localTransform() const OVERRIDE { return m_localTransform; }
 
+#if ENABLE(ASSERT)
+    virtual bool paintInvalidationStateIsDirty() const OVERRIDE  { return RenderSVGContainer::paintInvalidationStateIsDirty() || m_didTransformToRootUpdate; }
+#endif
+
     bool m_needsTransformUpdate : 1;
     bool m_didTransformToRootUpdate : 1;
     AffineTransform m_localTransform;