Bug 1420431 - Allow WebElement to be returned from GeckoDriver. r=maj…

…a_zf

Instead of having to assign resp.body.value explicitly when dealing
with WebElements, this makes it possible to return WebElement
references directly from GeckoDriver command handlers.  This was
not possible in the past because web element representations were
just plain object literals.

MozReview-Commit-ID: EPqXJ2gpNen

testing/marionette/driver.js

@@ -2171,12 +2171,12 @@ GeckoDriver.prototype.findElements = async function(cmd, resp) {
  * @throws {UnexpectedAlertOpenError}
  *     A modal dialog is open, blocking this operation.
  */
-GeckoDriver.prototype.getActiveElement = async function(cmd, resp) {
+GeckoDriver.prototype.getActiveElement = async function() {
   assert.content(this.context);
   assert.window(this.getCurrentWindow());
   this._assertAndDismissModal();
 
-  resp.body.value = await this.listener.getActiveElement();
+  return this.listener.getActiveElement();
 };
 
 /**

testing/marionette/server.js

@@ -18,6 +18,7 @@ Cu.import("resource://gre/modules/XPCOMUtils.jsm");
 
 Cu.import("chrome://marionette/content/assert.js");
 const {GeckoDriver} = Cu.import("chrome://marionette/content/driver.js", {});
+const {WebElement} = Cu.import("chrome://marionette/content/element.js", {});
 const {
   error,
   UnknownCommandError,
@@ -27,8 +28,7 @@ const {
   Message,
   Response,
 } = Cu.import("chrome://marionette/content/message.js", {});
-const {DebuggerTransport} =
-    Cu.import("chrome://marionette/content/transport.js", {});
+const {DebuggerTransport} = Cu.import("chrome://marionette/content/transport.js", {});
 
 XPCOMUtils.defineLazyServiceGetter(
     this, "env", "@mozilla.org/process/environment;1", "nsIEnvironment");
@@ -560,7 +560,7 @@ server.TCPConnection = class {
     let rv = await fn.bind(this.driver)(cmd, resp);
 
     if (typeof rv != "undefined") {
-      if (typeof rv != "object") {
+      if (rv instanceof WebElement || typeof rv != "object") {
         resp.body = {value: rv};
       } else {
         resp.body = rv;