Change to old clipboard copy technique, to support chrome and older firefox versions

external_js/clipboard-helper.js

@@ -0,0 +1,16 @@
+/*
+ * Source: https://github.com/mdn/webextensions-examples/tree/master/context-menu-copy-link-with-types
+ */
+function copyToClipboard(text) {
+    function oncopy(event) {
+        document.removeEventListener("copy", oncopy, true);
+
+        event.stopImmediatePropagation();
+
+        event.preventDefault();
+        event.clipboardData.setData("text/plain", text);
+    }
+    document.addEventListener("copy", oncopy, true);
+
+    document.execCommand("copy");
+}