feat(Page): teach Page.setContent to wait for resources to load (#1152)

This patch adds "options" parameter to the `page.setContent` method. The
parameter is the same as a navigation parameter and allows to specify
maximum timeout to wait for resources to be loaded, as well as to
describe events that should be emitted before the setContent operation
would be considered successful.

Fixes #728.

lib/Page.js

@@ -437,13 +437,17 @@ class Page extends EventEmitter {
 
   /**
    * @param {string} html
+   * @param {!Object=} options
    */
-  async setContent(html) {
-    await this.evaluate(html => {
-      document.open();
-      document.write(html);
-      document.close();
-    }, html);
+  async setContent(html, options) {
+    await Promise.all([
+      this.evaluate(html => {
+        document.open();
+        document.write(html);
+        document.close();
+      }, html),
+      this.waitForNavigation(options),
+    ]);
   }
 
   /**