Bug 1555523. r=alchen

Differential Revision: https://phabricator.services.mozilla.com/D33639

--HG--
extra : moz-landing-system : lando

parser/html/javasrc/Tokenizer.java

@@ -3949,12 +3949,9 @@ public class Tokenizer implements Locator {
                                     tokenHandler.characters(
                                             Tokenizer.LT_SOLIDUS, 0, 2);
                                     emitStrBuf();
-                                    if (c == '\u0000') {
-                                        emitReplacementCharacter(buf, pos);
-                                    } else {
-                                        cstart = pos; // don't drop the
-                                        // character
-                                    }
+                                    cstart = pos; // don't drop the
+                                                  // character
+                                    reconsume = true;
                                     state = transition(state, returnState, reconsume, pos);
                                     continue stateloop;
                             }

parser/html/nsHtml5Tokenizer.cpp

@@ -2360,11 +2360,8 @@ stateloop:
               default: {
                 tokenHandler->characters(nsHtml5Tokenizer::LT_SOLIDUS, 0, 2);
                 emitStrBuf();
-                if (c == '\0') {
-                  emitReplacementCharacter(buf, pos);
-                } else {
-                  cstart = pos;
-                }
+                cstart = pos;
+                reconsume = true;
                 state = P::transition(mViewSource, returnState, reconsume, pos);
                 NS_HTML5_CONTINUE(stateloop);
               }