Revert "Print Preview Componentization: Fix document title"

This reverts commit b0314879.

Reason for revert: Seems to have broken a number of print browsertests on Win 7

https://ci.chromium.org/p/chromium/builders/luci.chromium.ci/Win7%20Tests%20%28dbg%29%281%29/69834

Original change's description:
> Print Preview Componentization: Fix document title
> 
> Set the document title to the title of the tab being printed, so that
> the task manager will show the correct task title.
> 
> Bug: 773928
> Cq-Include-Trybots: luci.chromium.try:closure_compilation
> Change-Id: If8f7fec12bd81cca71bdccf3fb9f040ac17bc3f0
> Reviewed-on: https://chromium-review.googlesource.com/1104985
> Reviewed-by: Demetrios Papadopoulos <dpapad@chromium.org>
> Commit-Queue: Rebekah Potter <rbpotter@chromium.org>
> Cr-Commit-Position: refs/heads/master@{#568487}

TBR=dpapad@chromium.org,rbpotter@chromium.org

Change-Id: Ibafe5312ce179f07a5342cd512342873ab0687f2
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Bug: 773928
Cq-Include-Trybots: luci.chromium.try:closure_compilation
Reviewed-on: https://chromium-review.googlesource.com/1107897Reviewed-by: Martin Šrámek <msramek@chromium.org>
Commit-Queue: Martin Šrámek <msramek@chromium.org>
Cr-Commit-Position: refs/heads/master@{#568811}

chrome/browser/resources/print_preview/new/app.js

@@ -285,9 +285,6 @@ Polymer({
         this.recentDestinations_);
     this.isInAppKioskMode_ = settings.isInAppKioskMode;
     this.isInKioskAutoPrintMode_ = settings.isInKioskAutoPrintMode;
-
-    // This is only visible in the task manager.
-    document.head.querySelector('title').textContent = settings.documentTitle;
   },
 
   /**