Bug 1304531 - Remove CPOW usage from browser_newtabwebchannel.js. r=Felipe

This one also probably wouldn't cause problems, but getting rid of the CPOW
was so easy, I did so anyway.

MozReview-Commit-ID: IWNwpKF52gI

--HG--
extra : rebase_source : 909cf7fb351f9a7d27e806616e48592f169dae12

browser/components/newtab/tests/browser/browser_newtabwebchannel.js

@@ -241,7 +241,7 @@ add_task(function* open_webchannel_reload() {
     is(NewTabWebChannel.numBrowsers, 1, "One target expected");
     is(target.browser, browser, "Same browser");
 
-    browser.contentWindow.location.reload();
+    browser.reload();
   });
 
   Cu.forceGC();