use iframe-ed command-line

src/command-line/command-line-frame.js

@@ -0,0 +1,19 @@
+import './command-line-frame.scss';
+
+export default class CommandLineFrame {
+  constructor(win, initial = '') {
+    let url = browser.runtime.getURL('build/command-line.html') +
+      '#' + encodeURIComponent(initial);
+
+    let element = window.document.createElement('iframe');
+    element.src = url;
+    element.className = 'vimvixen-command-line-frame';
+    win.document.body.append(element);
+
+    this.element = element;
+  }
+
+  remove() {
+    this.element.remove();
+  }
+}