Isolated elements at end of line are not being correctly treated

LayoutTests/fast/text/output-isolate-at-end-of-line-crash.html

+<meta content="text/html; charset=iso-8859-8" http-equiv=content-Type>><mark id=tCF4></mark>>>><menu></menu>><output style="shape-outside: url(&quot; ">hCi*
+<style>
+        @keyframes cfpulse1 { 0% { opacity: 0.4205;  } 
+                 100% { opacity: 0.9435;  } }
+         * { animation-name: cfpulse86; overflow-y: -webkit-paged-y; width: 49em;  }
+         .c21 { flex-wrap: wrap-reverse; content: "{L|+^ abju#hEv}w=[zq.,#$0Z?M1X ;    } |vE1T9|()e|E.   msL&$ ^vm(    b6PV=THG "; padding: 36em 2327585803544415220860593003835739938188279140813781283479458423727613613378118205529738120838167666139579329217634396866342577059235016881159190 14 0.248468em;</style><script>
+         var docElement = document.body ? document.body : document.documentElement;
+         if (window.testRunner)
+                testRunner.dumpAsText();
+
+         function initCF() {
+                 try { tCF54 = document.createElementNS("http://www.w3.org/1999/xhtml", "label"); } catch(e) {}
+                 try { tCF54.setAttribute("class", "c21"); } catch(e) {}
+                 try { docElement.appendChild(tCF54); } catch(e) {}
+                 try { tCF55 = document.createElementNS("http://www.w3.org/1998/Math/MathML", "mn"); } catch(e) {}
+                 try { docElement.appendChild(tCF55); } catch(e) {}
+                 try { tCF59 = document.createTextNode(" This test has passed if it doesn't crash under ASAN"); } catch(e) {}
+         try { docElement.appendChild(tCF59); } catch(e) {}
+         setTimeout("tCFcrash()", 198);
+ }
+ document.addEventListener("DOMContentLoaded", initCF, false);
+ function tCFcrash() {
+         setTimeout('try { if (tCF55 != docElement) { tCF55.parentNode.removeChild(tCF55); }} catch(e) {}', 287);
+         setTimeout('try { tCF112.insertAdjacentHTML("afterend", > } catch(e) {}', 159);
+         setTimeout('try { tCF4.style.display = "table"} catch(e) {}', 384);
+         }</script>>