Fix link highlights on links that contain images.

Source/web/LinkHighlight.cpp

Index: Source/web/LinkHighlight.cpp
diff --git a/Source/web/LinkHighlight.cpp b/Source/web/LinkHighlight.cpp
index 34aa09d71558e9a25fb4d87b3d5c4cd6e0b13d6d..33fdae2585f9c7789248217318454fef775f85f3 100644
--- a/Source/web/LinkHighlight.cpp
+++ b/Source/web/LinkHighlight.cpp
@@ -49,6 +49,7 @@
 #include "public/platform/WebRect.h"
 #include "public/platform/WebSize.h"
 #include "wtf/CurrentTime.h"
+#include "wtf/Vector.h"
 
 using namespace WebCore;
 
@@ -184,6 +185,38 @@ static void addQuadToPath(const FloatQuad& quad, Path& path)
     path.closeSubpath();
 }
 
+void LinkHighlight::computeQuads(RenderObject* renderer, Vector<FloatQuad>& outQuads) const
+{
+    if (!renderer)
+        return;
+
+    Vector<FloatQuad> newQuads;
+    renderer->absoluteQuads(newQuads);
+
+    // As an optimization and to ensure we draw a rounded highlight, ensure we don't add
+    // any quads that are contained in an existing quad. If there is more than one
+    // quad returned they won't get rounded (see FIXME in computeHighlightLayerPathAndPosition).
+    for (unsigned i = 0; i < outQuads.size(); ++i) {

[aelias_OOO_until_Jul13, 2014/01/11 00:22:45]

Nit: use size_t instead of unsigned

+        for (unsigned newIx = newQuads.size(); newIx > 0; --newIx) {
+            if (outQuads[i].containsQuad(newQuads[newIx - 1]))
+                newQuads.remove(newIx - 1);

[aelias_OOO_until_Jul13, 2014/01/11 00:22:45]

removal is an O(n) operation on a Vector.  In addition this is within two loops
inside a recursive call.  I'm concerned the running time of this algorithm may
become pathological.  Could you give some thought about how this could be done
more efficiently?

+        }
+    }
+
+    outQuads.append(newQuads);
+
+    // For inline elements, absoluteQuads will return a line box based on the line-height
+    // and font metrics, which is technically incorrect as replaced elements like images
+    // should use their intristic height and expand the linebox  as needed. To get an
+    // appropriately sized highlight we descend into the children and have them add their
+    // boxes.
+    if (renderer->isInline()) {
+        for (RenderObject* child = renderer->firstChild(); child; child = child->nextSibling())
+            computeQuads(child, outQuads);
+    }
+
+}
+
 bool LinkHighlight::computeHighlightLayerPathAndPosition(RenderLayer* compositingLayer)
 {
     if (!m_node || !m_node->renderer() || !m_currentGraphicsLayer)
@@ -193,7 +226,7 @@ bool LinkHighlight::computeHighlightLayerPathAndPosition(RenderLayer* compositin
 
     // Get quads for node in absolute coordinates.
     Vector<FloatQuad> quads;
-    m_node->renderer()->absoluteQuads(quads);
+    computeQuads(m_node->renderer(), quads);
     ASSERT(quads.size());
 
     // Adjust for offset between target graphics layer and the node's renderer.