Refactor LayoutInline::addOutlineRects to avoid tricky logic to avoid dups

Source/core/layout/LayoutBlock.cpp

Index: Source/core/layout/LayoutBlock.cpp
diff --git a/Source/core/layout/LayoutBlock.cpp b/Source/core/layout/LayoutBlock.cpp
index badc7785b8b72716b8de09760e668a4364650ef9..652b3174e6ab36212c53cce33965e20b9622c058 100644
--- a/Source/core/layout/LayoutBlock.cpp
+++ b/Source/core/layout/LayoutBlock.cpp
@@ -2597,12 +2597,8 @@ void LayoutBlock::addOutlineRects(Vector<LayoutRect>& rects, const LayoutPoint&
         }
     }
 
-    if (inlineElementContinuation) {
-        Vector<LayoutRect> inlineOutlineRects;
-        // We need to give the LayoutInline a clean vector to let it add focus ring rects of line boxes.
-        inlineElementContinuation->addOutlineRects(inlineOutlineRects, additionalOffset + (inlineElementContinuation->containingBlock()->location() - location()));
-        rects.appendVector(inlineOutlineRects);
-    }
+    if (inlineElementContinuation)

[chrishtr, 2015/08/07 23:35:31]

Can this code just be deleted, and then the special casing in
LayoutBoxModelObject::addOutlineRectsForDescendant is gone?

[Xianzhu, 2015/08/07 23:56:23]

They are for different cases. You can treat the addOutlineRects a
two-dimensional action:
- parent-children dimension
- and continuation dimension.

The code path (and special case) in
LayoutBoxModelObject::addOutlineRectsForDescendant() is in parent-children
dimension, where we don't want descendant LayoutInline to add duplicated line
boxes.

This 'inlineElementContinuation' code is executed in continuation dimension as
  LayoutInline::addOutlineRects()
 -> (same 'this') LayoutInline::addOutlineRectsForChildrenAndContinuation()
 -> (block continuation) LayoutBlock::addOutlineRects()
 -> (inline continuation) LayoutInline::addOutlineRects()
Here the last LayoutInline is not a descendant of any previous objects which
have added outline rects, so we call addOutlineRects() to let it add all outline
rects of it.

[chrishtr, 2015/08/08 02:42:00]

Then I don't understand where the potential duplication of outline rects is
coming from. I thought this was the place where outline rects were being
generated that duplicated things and necessitated the special case in
LayoutBoxModelObject::addOutlineRectsForDescendant(). I guess not? Where do the
duplicates come from?

+        inlineElementContinuation->addOutlineRects(rects, additionalOffset + (inlineElementContinuation->containingBlock()->location() - location()));
 }
 
 void LayoutBlock::computeSelfHitTestRects(Vector<LayoutRect>& rects, const LayoutPoint& layerOffset) const