[matchbrackets addon] Add highlightNonMatching option

It's not uncommon to have non-matching brackets in MediaWiki
wikitext source code. This is not always an error. Another
reason why we want to disable this feature is that it's rather
distracting while typing. We temporarily patched our copy of
the addon, but think it's worth having a proper config flag.

https://gerrit.wikimedia.org/r/656119

Author: thiemowmde

addon/edit/matchbrackets.js

@@ -80,11 +80,12 @@
 
   function matchBrackets(cm, autoclear, config) {
     // Disable brace matching in long lines, since it'll cause hugely slow updates
-    var maxHighlightLen = cm.state.matchBrackets.maxHighlightLineLength || 1000;
+    var maxHighlightLen = cm.state.matchBrackets.maxHighlightLineLength || 1000,
+      highlightNonMatching = config && config.highlightNonMatching;
     var marks = [], ranges = cm.listSelections();
     for (var i = 0; i < ranges.length; i++) {
       var match = ranges[i].empty() && findMatchingBracket(cm, ranges[i].head, config);
-      if (match && cm.getLine(match.from.line).length <= maxHighlightLen) {
+      if (match && (match.match || highlightNonMatching !== false) && cm.getLine(match.from.line).length <= maxHighlightLen) {
         var style = match.match ? "CodeMirror-matchingbracket" : "CodeMirror-nonmatchingbracket";
         marks.push(cm.markText(match.from, Pos(match.from.line, match.from.ch + 1), {className: style}));
         if (match.to && cm.getLine(match.to.line).length <= maxHighlightLen)

doc/manual.html

@@ -2443,6 +2443,8 @@ <h2 id="addons">Addons</h2>
         <dl>
           <dt><strong><code>afterCursor</code></strong></dt>
           <dd>Only use the character after the start position, never the one before it.</dd>
+          <dt><strong><code>highlightNonMatching</code></strong></dt>
+          <dd>Also highlight pairs of non-matching as well as stray brackets. Enabled by default.</dd>
           <dt><strong><code>strict</code></strong></dt>
           <dd>Causes only matches where both brackets are at the same side of the start position to be considered.</dd>
           <dt><strong><code>maxScanLines</code></strong></dt>