Change FilesApp UI tests to support html imports polyfill

Add switches to file_manager_uitest.cc browser_test
to disable 'ShadowDOMV0', 'CustomElementsV0', 'HTMLImports'.

The UI tests do not support loading chrome://resource URLs
and the html-imports polyfill silently fails for everything
if it encounters a resource that it can't load.

html-imports also requires polymer2.

So in order to make html-imports run with polymer2, and
without failing, all
//third_party/polymer/v1_0/components-chromium/ polymer
elements, and others in file_manager are copied
into the file_manager/test/gen directory and modified to
refer to a valid file path.

The polymer1 dir is removed, and the polymer2 directory
is renamed to polymer so that all elements now refer
to the correct path for polymer2.

Update create_test_main.py generation script to do this copying
and update paths correctly.

Deleted chrome/test/data/chromeos/file_manager/html-imports.js
There was an earlier plan to use this file with modifications,
but this file is now not needed.

Bug: 924873
Change-Id: Ie0dfdd660c26e9f8c6e4ed843dc4e35fcaa1b34f
Reviewed-on: https://chromium-review.googlesource.com/c/1488484
Commit-Queue: Joel Hockey <joelhockey@chromium.org>
Reviewed-by: Luciano Pacheco <lucmult@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636176}
4 files changed