<html>
    <head>
      <base href="https://bugs.webkit.org/" />
    </head>
    <body><table border="1" cellspacing="0" cellpadding="8">
        <tr>
          <th>Bug ID</th>
          <td><a class="bz_bug_link 
          bz_status_NEW "
   title="NEW - ASSERTION FAILED: !lookupForWriting(Extractor::extract(entry)).second"
   href="https://bugs.webkit.org/show_bug.cgi?id=167142">167142</a>
          </td>
        </tr>

        <tr>
          <th>Summary</th>
          <td>ASSERTION FAILED: !lookupForWriting(Extractor::extract(entry)).second
          </td>
        </tr>

        <tr>
          <th>Classification</th>
          <td>Unclassified
          </td>
        </tr>

        <tr>
          <th>Product</th>
          <td>WebKit
          </td>
        </tr>

        <tr>
          <th>Version</th>
          <td>WebKit Nightly Build
          </td>
        </tr>

        <tr>
          <th>Hardware</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>OS</th>
          <td>Unspecified
          </td>
        </tr>

        <tr>
          <th>Status</th>
          <td>NEW
          </td>
        </tr>

        <tr>
          <th>Severity</th>
          <td>Normal
          </td>
        </tr>

        <tr>
          <th>Priority</th>
          <td>P2
          </td>
        </tr>

        <tr>
          <th>Component</th>
          <td>New Bugs
          </td>
        </tr>

        <tr>
          <th>Assignee</th>
          <td>webkit-unassigned&#64;lists.webkit.org
          </td>
        </tr>

        <tr>
          <th>Reporter</th>
          <td>ryanhaddad&#64;apple.com
          </td>
        </tr></table>
      <p>
        <div>
        <pre>ASSERTION FAILED: !lookupForWriting(Extractor::extract(entry)).second
/Volumes/Data/slave/elcapitan-debug/build/WebKitBuild/Debug/usr/local/include/wtf/HashTable.h(987) : ValueType *WTF::HashTable&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::KeyValuePairTraits, WebCore::FontDataCacheKeyTraits&gt;::reinsert(ValueType &amp;&amp;) [Key = WebCore::FontPlatformData, Value = WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, Extractor = WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, HashFunctions = WebCore::FontDataCacheKe
1   0x10630d7e0 WTFCrash
2   0x1095e10e1 WTF::HashTable&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::KeyValuePairTraits, WebCore::FontDataCacheKeyTraits&gt;::reinsert(WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;&amp;&amp;)
3   0x1095e0f1d WTF::HashTable&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::KeyValuePairTraits, WebCore::FontDataCacheKeyTraits&gt;::rehash(unsigned int, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;*)
4   0x1095e3b31 WTF::HashTable&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::KeyValuePairTraits, WebCore::FontDataCacheKeyTraits&gt;::shrink()
5   0x1095e3a89 WTF::HashTable&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::KeyValuePairTraits, WebCore::FontDataCacheKeyTraits&gt;::remove(WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;*)
6   0x1095e3a1d WTF::HashTable&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::KeyValuePairTraits, WebCore::FontDataCacheKeyTraits&gt;::removeAndInvalidateWithoutEntryConsistencyCheck(WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;*)
7   0x1095e3999 WTF::HashTable&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::KeyValuePairTraits, WebCore::FontDataCacheKeyTraits&gt;::removeWithoutEntryConsistencyCheck(WTF::HashTableIterator&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKey
8   0x1095e3886 WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::remove(WTF::HashTableIteratorAdapter&lt;WTF::HashTable&lt;WebCore::FontPlatformData, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt;, WTF::KeyValuePairKeyExtractor&lt;WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;, WebCore::FontDataCacheKeyHash, WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::KeyValuePairTraits, WebCore::FontDataCacheKeyTraits&gt;, WTF::KeyValuePair&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;)
9   0x1095da3b6 WTF::HashMap&lt;WebCore::FontPlatformData, WTF::RefPtr&lt;WebCore::Font&gt;, WebCore::FontDataCacheKeyHash, WebCore::FontDataCacheKeyTraits, WTF::HashTraits&lt;WTF::RefPtr&lt;WebCore::Font&gt; &gt; &gt;::remove(WebCore::FontPlatformData const&amp;)
10  0x1095d937d WebCore::FontCache::purgeInactiveFontData(unsigned int)
11  0x1095d99f3 WebCore::FontCache::invalidate()
12  0x1095ec3d6 WebCore::invalidateFontCache()
13  0x1095ea373 WebCore::fontCacheRegisteredFontsChangedNotificationCallback(__CFNotificationCenter*, void*, __CFString const*, void const*, __CFDictionary const*)
14  0x7fff982dbb1c __CFNOTIFICATIONCENTER_IS_CALLING_OUT_TO_AN_OBSERVER__
15  0x7fff982dbaaf ___CFXRegistrationPost_block_invoke
16  0x7fff982dba27 _CFXRegistrationPost
17  0x7fff982db792 ___CFXNotificationPost_block_invoke
18  0x7fff98298542 -[_CFXNotificationRegistrar find:object:observer:enumerator:]
19  0x7fff98297795 _CFXNotificationPost
20  0x7fff982e1395 CFNotificationCenterPostNotification
21  0x7fff870fd0b9 AsynchronousLocalNotificationTimerCallBack(__CFRunLoopTimer*, void*)
22  0x7fff982cdaf4 __CFRUNLOOP_IS_CALLING_OUT_TO_A_TIMER_CALLBACK_FUNCTION__
23  0x7fff982cd783 __CFRunLoopDoTimer
24  0x7fff982cd2da __CFRunLoopDoTimers
25  0x7fff982c47d1 __CFRunLoopRun
26  0x7fff982c3e38 CFRunLoopRunSpecific
27  0x7fff951a5935 RunCurrentEventLoopInMode
28  0x7fff951a576f ReceiveNextEventCommon
29  0x7fff951a55af _BlockUntilNextEventMatchingListInModeWithFilter
30  0x7fff8a7a6df6 _DPSNextEvent
31  0x7fff8a7a6226 -[NSApplication _nextEventMatchingEventMask:untilDate:inMode:dequeue:]

Seen with imported/w3c/web-platform-tests/html/semantics/embedded-content/the-img-element/srcset/select-an-image-source.html here <a href="https://build.webkit.org/results/Apple%20El%20Capitan%20Debug%20WK2%20(Tests)/r210825%20(10434)/results.html">https://build.webkit.org/results/Apple%20El%20Capitan%20Debug%20WK2%20(Tests)/r210825%20(10434)/results.html</a></pre>
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