Fix double execution in Code demo (#5152)

* Fix double execution in Code demo

PR #5037  fixed double execution of the run button on mobile.  But the link button and other events still suffer from double execution.  This PR moves the fix from the run button to the central bind function so that it applies universally.

* Pass the event to the user function

Not used but good to have.

demos/code/code.js

@@ -188,7 +188,12 @@ Code.bindClick = function(el, func) {
     el = document.getElementById(el);
   }
   el.addEventListener('click', func, true);
-  el.addEventListener('touchend', func, true);
+  function touchFunc(e) {
+    // Prevent code from being executed twice on touchscreens.
+    e.preventDefault();
+    func(e);
+  }
+  el.addEventListener('touchend', touchFunc, true);
 };
 
 /**
@@ -549,14 +554,8 @@ Code.initLanguage = function() {
 /**
  * Execute the user's code.
  * Just a quick and dirty eval.  Catch infinite loops.
- * @param {Event} event Event created from listener bound to the function.
  */
-Code.runJS = function(event) {
-  // Prevent code from being executed twice on touchscreens.
-  if (event.type == 'touchend') {
-    event.preventDefault();
-  }
-
+Code.runJS = function() {
   Blockly.JavaScript.INFINITE_LOOP_TRAP = 'checkTimeout();\n';
   var timeouts = 0;
   var checkTimeout = function() {