[epiphany/mcatanzaro/highlightjs-10.2.1] Update to highlight.js 10.2.1

[Michael Catanzaro <mcatanzaro src gnome org>]

commit a348898ff811c61b33e38071f9a03570eedd2aa0
Author: Michael Catanzaro <mcatanzaro gnome org>
Date:   Mon Sep 21 09:13:00 2020 -0500

    Update to highlight.js 10.2.1
    
    Another day, another highlight.js release.

 third-party/highlightjs/highlight.js | 69 ++++++++++++++++++++++++------------
 1 file changed, 47 insertions(+), 22 deletions(-)
---
diff --git a/third-party/highlightjs/highlight.js b/third-party/highlightjs/highlight.js
index cb421eea3..08b11e98c 100644
--- a/third-party/highlightjs/highlight.js
+++ b/third-party/highlightjs/highlight.js
@@ -1,5 +1,5 @@
 /*
-  Highlight.js 10.2.0 (da7d149b)
+  Highlight.js 10.2.0 (519f7798)
   License: BSD-3-Clause
   Copyright (c) 2006-2020, Ivan Sagalaev
 */
@@ -913,7 +913,7 @@ var hljs = (function () {
       }
 
       resumingScanAtSamePosition() {
-        return this.regexIndex != 0;
+        return this.regexIndex !== 0;
       }
 
       considerAll() {
@@ -930,15 +930,55 @@ var hljs = (function () {
       exec(s) {
         const m = this.getMatcher(this.regexIndex);
         m.lastIndex = this.lastIndex;
-        const result = m.exec(s);
+        let result = m.exec(s);
+
+        // The following is because we have no easy way to say "resume scanning at the
+        // existing position but also skip the current rule ONLY". What happens is
+        // all prior rules are also skipped which can result in matching the wrong
+        // thing. Example of matching "booger":
+
+        // our matcher is [string, "booger", number]
+        //
+        // ....booger....
+
+        // if "booger" is ignored then we'd really need a regex to scan from the
+        // SAME position for only: [string, number] but ignoring "booger" (if it
+        // was the first match), a simple resume would scan ahead who knows how
+        // far looking only for "number", ignoring potential string matches (or
+        // future "booger" matches that might be valid.)
+
+        // So what we do: We execute two matchers, one resuming at the same
+        // position, but the second full matcher starting at the position after:
+
+        //     /--- resume first regex match here (for [number])
+        //     |/---- full match here for [string, "booger", number]
+        //     vv
+        // ....booger....
+
+        // Which ever results in a match first is then used. So this 3-4 step
+        // process essentially allows us to say "match at this position, excluding
+        // a prior rule that was ignored".
+        //
+        // 1. Match "booger" first, ignore. Also proves that [string] does non match.
+        // 2. Resume matching for [number]
+        // 3. Match at index + 1 for [string, "booger", number]
+        // 4. If #2 and #3 result in matches, which came first?
+        if (this.resumingScanAtSamePosition()) {
+          if (result && result.index === this.lastIndex) ; else { // use the second matcher result
+            const m2 = this.getMatcher(0);
+            m2.lastIndex = this.lastIndex + 1;
+            result = m2.exec(s);
+          }
+        }
+
         if (result) {
           this.regexIndex += result.position + 1;
-          if (this.regexIndex === this.count) { // wrap-around
-            this.regexIndex = 0;
+          if (this.regexIndex === this.count) {
+            // wrap-around to considering all matches again
+            this.considerAll();
           }
         }
 
-        // this.regexIndex = 0;
         return result;
       }
     }
@@ -1541,14 +1581,6 @@ var hljs = (function () {
         }
       }
 
-      /**
-       * Advance a single character
-       */
-      function advanceOne() {
-        mode_buffer += codeToHighlight[index];
-        index += 1;
-      }
-
       /**
        * Handle matching but then ignoring a sequence of text
        *
@@ -1778,20 +1810,13 @@ var hljs = (function () {
             // considered for a potential match
             resumeScanAtSamePosition = false;
           } else {
-            top.matcher.lastIndex = index;
             top.matcher.considerAll();
           }
+          top.matcher.lastIndex = index;
 
           const match = top.matcher.exec(codeToHighlight);
           // console.log("match", match[0], match.rule && match.rule.begin)
 
-          // if our failure to match was the result of a "resumed scan" then we
-          // need to advance one position and revert to full scanning before we
-          // decide there are truly no more matches at all to be had
-          if (!match && top.matcher.resumingScanAtSamePosition()) {
-            advanceOne();
-            continue;
-          }
           if (!match) break;
 
           const beforeMatch = codeToHighlight.substring(index, match.index);