[show-hint addon] Fix event delegation for UL/LI

It's possible to provide custom markup for hint elements that are LI
tags and that breaks event delegation logic that expects UL to have
text-only LI nodes. As a result if you have elements inside LI and
click/dblclick on those, nothing happens and selected hint is not
applied. The fix improves event delegation in the way to find nearest
parent element to event target that is a hint element at the same time.

addon/hint/show-hint.js

 (function() {
   "use strict";
 
+  var HINT_ELEMENT_CLASS        = "CodeMirror-hint";
+  var ACTIVE_HINT_ELEMENT_CLASS = "CodeMirror-hint-active";
+
   CodeMirror.showHint = function(cm, getHints, options) {
     // We want a single cursor position.
     if (cm.somethingSelected()) return;
@@ -152,7 +155,7 @@
     var completions = data.list;
     for (var i = 0; i < completions.length; ++i) {
       var elt = hints.appendChild(document.createElement("li")), cur = completions[i];
-      var className = "CodeMirror-hint" + (i ? "" : " CodeMirror-hint-active");
+      var className = HINT_ELEMENT_CLASS + (i ? "" : " " + ACTIVE_HINT_ELEMENT_CLASS);
       if (cur.className != null) className = cur.className + " " + className;
       elt.className = className;
       if (cur.render) cur.render(elt, data, cur);
@@ -216,13 +219,15 @@
     });
 
     CodeMirror.on(hints, "dblclick", function(e) {
-      var t = e.target || e.srcElement;
-      if (t.hintId != null) {widget.changeActive(t.hintId); widget.pick();}
+      var t = widget.getHintElement(hints, e.target || e.srcElement);
+      if (t && t.hintId != null) {widget.changeActive(t.hintId); widget.pick();}
     });
+
     CodeMirror.on(hints, "click", function(e) {
-      var t = e.target || e.srcElement;
-      if (t.hintId != null) widget.changeActive(t.hintId);
+      var t = widget.getHintElement(hints, e.target || e.srcElement);
+      if (t && t.hintId != null) widget.changeActive(t.hintId);
     });
+
     CodeMirror.on(hints, "mousedown", function() {
       setTimeout(function(){cm.focus();}, 20);
     });
@@ -257,9 +262,9 @@
         i = avoidWrap ? 0  : this.data.list.length - 1;
       if (this.selectedHint == i) return;
       var node = this.hints.childNodes[this.selectedHint];
-      node.className = node.className.replace(" CodeMirror-hint-active", "");
+      node.className = node.className.replace(" " + ACTIVE_HINT_ELEMENT_CLASS, "");
       node = this.hints.childNodes[this.selectedHint = i];
-      node.className += " CodeMirror-hint-active";
+      node.className += " " + ACTIVE_HINT_ELEMENT_CLASS;
       if (node.offsetTop < this.hints.scrollTop)
         this.hints.scrollTop = node.offsetTop - 3;
       else if (node.offsetTop + node.offsetHeight > this.hints.scrollTop + this.hints.clientHeight)
@@ -269,6 +274,25 @@
 
     screenAmount: function() {
       return Math.floor(this.hints.clientHeight / this.hints.firstChild.offsetHeight) || 1;
+    },
+
+    getHintElement: function (parentEl, el) {
+      while (el && el !== parentEl && !this.isHintElement(el)) {
+        el = el.parentNode;
+      }
+
+      return el === parentEl
+        ? void(0)
+        : el
+      ;
+    },
+
+    isHintElement: function (el) {
+      return el &&
+             el.nodeName &&
+             el.nodeName.toUpperCase() === 'LI' &&
+             el.className.indexOf(HINT_ELEMENT_CLASS) >= 0
+      ;
     }
   };
 })();