Prevent infinite loops when trying to execute mappings recursively.

common/content/events.js

@@ -1018,6 +1018,7 @@ var Events = Module("events", {
             if (refeed)
                 for (let [i, event] in Iterator(refeed))
                     if (event.originalTarget) {
+                        util.dump("Re-feed " + i + " " + refeed.length + " " + (events.toString(event) || "").quote());
                         let evt = events.create(event.originalTarget.ownerDocument, event.type, event);
                         events.dispatch(event.originalTarget, evt, i == 0 && { skipmap: true });
                     }

common/content/mappings.js

@@ -110,7 +110,11 @@ var Map = Class("Map", {
         if (this.names[0] != ".") // FIXME: Kludge.
             mappings.repeat = repeat;
 
-        return dactyl.trapErrors(repeat);
+        dactyl.assert(!this.executing, "Attempt to execute mapping recursively");
+        this.executing = true;
+        let res = dactyl.trapErrors(repeat);
+        this.executing = false;
+        return res;
     }
 
 }, {

common/content/modes.js

@@ -387,7 +387,7 @@ var Modes = Module("modes", {
             }, options);
         },
 
-        toString: function () this.name,
+        get toStringParams() [this.name],
 
         valueOf: function () this.id,
 
@@ -411,14 +411,14 @@ var Modes = Module("modes", {
     }),
     StackElement: (function () {
         const StackElement = Struct("main", "extended", "params", "saved");
+        StackElement.className = "Modes.StackElement";
         StackElement.defaultValue("params", function () this.main.params);
+
         update(StackElement.prototype, {
-            toString: function () !loaded.modes ? this.main : "[mode " +
-                this.main.name +
-                (!this.extended ? "" :
-                   "(" + modes.all.filter(function (m) this.extended & m)
-                              .join("|") +
-                   ")") + "]"
+            get toStringParams() !loaded.modes ? this.main.name : [
+                this.main.name,
+                <>({ modes.all.filter(function (m) this.extended & m, this).map(function (m) m.name).join("|") })</>
+            ]
         });
         return StackElement;
     })(),

common/modules/base.jsm

@@ -769,7 +769,8 @@ Class.prototype = {
     toString: function () {
         if (this.toStringParams)
             var params = "(" + this.toStringParams.map(function (m) isArray(m)  ? "[" + m + "]" :
-                                                                    isString(m) ? m.quote() : String(m)) + ")";
+                                                                    isString(m) ? m.quote() : String(m))
+                                   .join(", ") + ")";
         return "[instance " + this.constructor.className + (params || "") + "]";
     },