Enable HitTestCache by default.

Source/core/layout/HitTestCache.cpp

 // Copyright (c) 2015 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "config.h"
 #include "core/layout/HitTestCache.h"
 
 #include "public/platform/Platform.h"
 
 namespace blink {
@@ skipping 15 matching lines @@
                     break;
                 }
                 metric = HitHistogramMetric::MISS_VALIDITY_RECT_MATCHES;
             }
         }
     }
     Platform::current()->histogramEnumeration("Event.HitTest", static_cast<int>(metric), static_cast<int>(HitHistogramMetric::MAX_HIT_METRIC));
     return result;
 }
 
-void HitTestCache::verifyCachedResult(const HitTestResult& expected, const HitTestResult& actual)
-{
-    ValidityHistogramMetric metric;
-    if (!actual.equalForCacheability(expected)) {
-        metric = expected.hitTestLocation().isRectBasedTest() ? ValidityHistogramMetric::INCORRECT_RECT_BASED_EXACT_MATCH : ValidityHistogramMetric::INCORRECT_POINT_EXACT_MATCH;
-        Platform::current()->histogramSparse("Event.HitTestValidityScore", static_cast<int>(actual.equalityScore(expected)));
-
-        // ASSERT that the cache hit is the same as the actual result.
-        ASSERT_NOT_REACHED();
-    } else {
-        metric = ValidityHistogramMetric::VALID_EXACT_MATCH;
-    }
-    Platform::current()->histogramEnumeration("Event.HitTestValidity", static_cast<int>(metric), static_cast<int>(ValidityHistogramMetric::MAX_VALIDITY_METRIC));
-}
-
 void HitTestCache::addCachedResult(const HitTestResult& result, uint64_t domTreeVersion)
 {
     if (!result.isCacheable())
         return;
 
     // If the result was a hit test on an LayoutPart and the request allowed
     // querying of the layout part; then the part hasn't been loaded yet.
     if (result.isOverWidget() && result.hitTestRequest().allowsChildFrameContent())
         return;
 
@@ skipping 18 matching lines @@
     m_updateIndex = 0;
     m_items.clear();
 }
 
 DEFINE_TRACE(HitTestCache)
 {
     visitor->trace(m_items);
 }
 
 } // namespace blink