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

Source/core/layout/LayoutBoxModelObject.cpp

Index: Source/core/layout/LayoutBoxModelObject.cpp
diff --git a/Source/core/layout/LayoutBoxModelObject.cpp b/Source/core/layout/LayoutBoxModelObject.cpp
index 322bb7e4a5ebb6323025e044c5ed1568a0ac6880..3fdd847e19d204854f8f835095ec7ef653f4b2a6 100644
--- a/Source/core/layout/LayoutBoxModelObject.cpp
+++ b/Source/core/layout/LayoutBoxModelObject.cpp
@@ -414,6 +414,15 @@ void LayoutBoxModelObject::addOutlineRectsForDescendant(const LayoutObject& desc
         return;
     }
 
+    if (descendant.isLayoutInline()) {
+        // As an optimization, an ancestor has added rects for its line boxes covering descendants'
+        // line boxes, so descendants don't need to add line boxes again. In particular, LayoutBlock

[chrishtr, 2015/08/10 21:54:10]

LayoutBlock is not necessarily the root entry point into addOutlineRects, there
is code that calls directly into the LayoutInline version. So rephrase to
indicate this, maybe:

"For example, if the parent is a LayoutBlock, it adds rects..."

[Xianzhu, 2015/08/10 21:57:13]

Done.

+        // adds rects for its RootOutlineBoxes, which cover the line boxes of this LayoutInline.
+        // So the LayoutInline needs to add rects for children and continuations only.
+        toLayoutInline(descendant).addOutlineRectsForChildrenAndContinuations(rects, additionalOffset);
+        return;
+    }
+
     descendant.addOutlineRects(rects, additionalOffset);
 }