Fix redundant calls to onEditText() (#3541)

This fixes an issue where onEditText() would be called unnecessarily
when the markdown editor lost focus.

Simplify the code by just listening for the 'input' event, which all our
target browsers support.

h/static/scripts/directive/markdown.js

@@ -22,7 +22,6 @@ module.exports = function($sanitize) {
     controller: function () {},
     link: function(scope, elem) {
       var input = elem[0].querySelector('.js-markdown-input');
-      var inputEl = angular.element(input);
       var output = elem[0].querySelector('.js-markdown-preview');
 
       /**
@@ -133,13 +132,12 @@ module.exports = function($sanitize) {
         scope.preview = !scope.preview;
       };
 
-      // React to the changes to the input
       var handleInputChange = debounce(function () {
         scope.$apply(function () {
           scope.onEditText({text: input.value});
         });
       }, 100);
-      inputEl.bind('blur change keyup', handleInputChange);
+      input.addEventListener('input', handleInputChange);
 
       // Re-render the markdown when the view needs updating.
       scope.$watch('text', function () {

h/static/scripts/directive/test/markdown-test.js

@@ -181,7 +181,7 @@ describe('markdown', function () {
       });
       var input = inputElement(editor);
       input.value = 'new text';
-      util.sendEvent(input, 'change');
+      util.sendEvent(input, 'input');
       assert.called(onEditText);
       assert.calledWith(onEditText, 'new text');
     });