Webpack (#1367)

* Replace gulp with webpack and npm scripts for JS compilation
* Set up Travis CI to commit compiled JS
* Restructure `js` directory; only one instance of npm, forum/admin are "submodules"
* Refactor JS initializers into Application subclasses
* Maintain partial compatibility API (importing from absolute paths) for extensions
* Remove minification responsibility from PHP asset compiler
* Restructure `less` directory

js/src/forum/components/EditPostComposer.js

@@ -0,0 +1,86 @@
+import ComposerBody from './ComposerBody';
+import icon from '../../common/helpers/icon';
+
+function minimizeComposerIfFullScreen(e) {
+  if (app.composer.isFullScreen()) {
+    app.composer.minimize();
+    e.stopPropagation();
+  }
+}
+
+/**
+ * The `EditPostComposer` component displays the composer content for editing a
+ * post. It sets the initial content to the content of the post that is being
+ * edited, and adds a header control to indicate which post is being edited.
+ *
+ * ### Props
+ *
+ * - All of the props for ComposerBody
+ * - `post`
+ */
+export default class EditPostComposer extends ComposerBody {
+  init() {
+    super.init();
+
+    this.editor.props.preview = e => {
+      minimizeComposerIfFullScreen(e);
+
+      m.route(app.route.post(this.props.post));
+    };
+  }
+
+  static initProps(props) {
+    super.initProps(props);
+
+    props.submitLabel = props.submitLabel || app.translator.trans('core.forum.composer_edit.submit_button');
+    props.confirmExit = props.confirmExit || app.translator.trans('core.forum.composer_edit.discard_confirmation');
+    props.originalContent = props.originalContent || props.post.content();
+    props.user = props.user || props.post.user();
+
+    props.post.editedContent = props.originalContent;
+  }
+
+  headerItems() {
+    const items = super.headerItems();
+    const post = this.props.post;
+
+    const routeAndMinimize = function(element, isInitialized) {
+      if (isInitialized) return;
+      $(element).on('click', minimizeComposerIfFullScreen);
+      m.route.apply(this, arguments);
+    };
+
+    items.add('title', (
+      <h3>
+        {icon('fas fa-pencil-alt')} {' '}
+        <a href={app.route.discussion(post.discussion(), post.number())} config={routeAndMinimize}>
+          {app.translator.trans('core.forum.composer_edit.post_link', {number: post.number(), discussion: post.discussion().title()})}
+        </a>
+      </h3>
+    ));
+
+    return items;
+  }
+
+  /**
+   * Get the data to submit to the server when the post is saved.
+   *
+   * @return {Object}
+   */
+  data() {
+    return {
+      content: this.content()
+    };
+  }
+
+  onsubmit() {
+    this.loading = true;
+
+    const data = this.data();
+
+    this.props.post.save(data).then(
+      () => app.composer.hide(),
+      this.loaded.bind(this)
+    );
+  }
+}