Fix invalidity in HitTestCache with LayoutParts.

Source/core/layout/LayoutPart.cpp

Index: Source/core/layout/LayoutPart.cpp
diff --git a/Source/core/layout/LayoutPart.cpp b/Source/core/layout/LayoutPart.cpp
index 3bd9e7fbba2e5aafaf2d74491450b2ac38532fee..9f2b2b4e0167d1d675be89690ce444a98a11205b 100644
--- a/Source/core/layout/LayoutPart.cpp
+++ b/Source/core/layout/LayoutPart.cpp
@@ -152,6 +152,12 @@ bool LayoutPart::nodeAtPointOverWidget(HitTestResult& result, const HitTestLocat
     // Check to see if we are really over the widget itself (and not just in the border/padding area).
     if ((inside || result.isRectBasedTest()) && !hadResult && result.innerNode() == node())
         result.setIsOverWidget(contentBoxRect().contains(result.localPoint()));
+
+    // Do not cache hit tests as we don't get appropriate callbacks to invalidate the cache.
+    // This includes the border and padding areas for simplicity.
+    if (inside)

[esprehn, 2015/08/10 21:22:02]

Why not just use the isOverWidget check we did above? That avoids the
borders/padding and we're already doing it anyway.

+        result.setCacheable(false);
+
     return inside;
 }