Make polymer a side-effect import in print preview *_css.js

The `Polymer` and `html` are unused in css js files.

Change-Id: Iee6a6d6df14562c769bd7723a4f35698cc8a7478
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2541702Reviewed-by: Rebekah Potter <rbpotter@chromium.org>
Commit-Queue: Matt Menard <mattme@google.com>
Cr-Commit-Position: refs/heads/master@{#828423}

chrome/browser/resources/print_preview/ui/destination_select_css.js

@@ -5,7 +5,7 @@
 import 'chrome://resources/cr_elements/shared_style_css.m.js';
 import 'chrome://resources/cr_elements/shared_vars_css.m.js';
 
-import {html, Polymer} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
+import 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
 
 const template = document.createElement('template');
 template.innerHTML = `

chrome/browser/resources/print_preview/ui/print_preview_shared_css.js

@@ -6,7 +6,7 @@ import 'chrome://resources/cr_elements/shared_style_css.m.js';
 import 'chrome://resources/cr_elements/shared_vars_css.m.js';
 import './print_preview_vars_css.js';
 
-import {html, Polymer} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
+import 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
 
 const template = document.createElement('template');
 template.innerHTML = `

chrome/browser/resources/print_preview/ui/print_preview_vars_css.js

@@ -4,7 +4,7 @@
 
 import 'chrome://resources/cr_elements/shared_vars_css.m.js';
 
-import {html, Polymer} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
+import 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
 
 const $_documentContainer = document.createElement('template');
 $_documentContainer.innerHTML = `{__html_template__}`;

chrome/browser/resources/print_preview/ui/throbber_css.js

@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-import {html, Polymer} from 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
+import 'chrome://resources/polymer/v3_0/polymer/polymer_bundled.min.js';
 
 const template = document.createElement('template');
 template.innerHTML = `