Implement a Hit Test Cache.

Source/core/layout/LayoutInline.cpp

Index: Source/core/layout/LayoutInline.cpp
diff --git a/Source/core/layout/LayoutInline.cpp b/Source/core/layout/LayoutInline.cpp
index 1d3343a002aad3c72ff27c2e18e582c5749e980d..3c8b0a963f9584f262803fde0fa76773e76eb5c9 100644
--- a/Source/core/layout/LayoutInline.cpp
+++ b/Source/core/layout/LayoutInline.cpp
@@ -814,7 +814,8 @@ bool LayoutInline::hitTestCulledInline(HitTestResult& result, const HitTestLocat
     generateCulledLineBoxRects(context, this);
 
     if (context.intersected()) {
-        updateHitTestResult(result, tmpLocation.point());
+        // TODO(dtapuska): Move the regionResult by accumulatedOffset
+        updateHitTestResult(result, tmpLocation.point(), result.validityRect());
         // We can not use addNodeToListBasedTestResult to determine if we fully enclose the hit-test area
         // because it can only handle rectangular targets.
         result.addNodeToListBasedTestResult(node(), locationInContainer);
@@ -1232,11 +1233,12 @@ void LayoutInline::childBecameNonInline(LayoutObject* child)
     splitFlow(beforeChild, newBox, child, oldContinuation);
 }
 
-void LayoutInline::updateHitTestResult(HitTestResult& result, const LayoutPoint& point)
+void LayoutInline::updateHitTestResult(HitTestResult& result, const LayoutPoint& point, const LayoutRect& rect)
 {
     if (result.innerNode())
         return;
 
+    result.intersectValidityRect(rect);
     Node* n = node();
     LayoutPoint localPoint(point);
     if (n) {