MD Settings: Eliminate remaining references to paper-dropdown-menu-light

ui/webui/resources/polymer_resources.grdp

 <?xml version="1.0" encoding="utf-8"?>
 <!--
   This file is generated.
   Please use 'src/tools/polymer/polymer_grdp_to_txt.py' and
   'src/tools/polymer/txt_to_polymer_grdp.py' to modify it, if possible.
 
   'polymer_grdp_to_txt.py' converts 'polymer_resources.grdp' to a plain list of
   used Polymer components:
     ...
     iron-iron-iconset/iron-iconset-extracted.js
@@ skipping 482 matching lines @@
              type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_PAPER_DROPDOWN_MENU_PAPER_DROPDOWN_MENU_ICONS_HTML"
              file="../../../third_party/polymer/v1_0/components-chromium/paper-dropdown-menu/paper-dropdown-menu-icons.html"
              type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_PAPER_DROPDOWN_MENU_PAPER_DROPDOWN_MENU_SHARED_STYLES_HTML"
              file="../../../third_party/polymer/v1_0/components-chromium/paper-dropdown-menu/paper-dropdown-menu-shared-styles.html"
              type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_PAPER_DROPDOWN_MENU_PAPER_DROPDOWN_MENU_HTML"
              file="../../../third_party/polymer/v1_0/components-chromium/paper-dropdown-menu/paper-dropdown-menu.html"
              type="chrome_html" />
-  <structure name="IDR_POLYMER_1_0_PAPER_DROPDOWN_MENU_PAPER_DROPDOWN_MENU_LIGHT_HTML"
-             file="../../../third_party/polymer/v1_0/components-chromium/paper-dropdown-menu/paper-dropdown-menu-light.html"
-             type="chrome_html" />
-  <structure name="IDR_POLYMER_1_0_PAPER_DROPDOWN_MENU_PAPER_DROPDOWN_MENU_LIGHT_EXTRACTED_JS"
-             file="../../../third_party/polymer/v1_0/components-chromium/paper-dropdown-menu/paper-dropdown-menu-light-extracted.js"
-             type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_PAPER_FAB_PAPER_FAB_EXTRACTED_JS"
              file="../../../third_party/polymer/v1_0/components-chromium/paper-fab/paper-fab-extracted.js"
              type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_PAPER_FAB_PAPER_FAB_HTML"
              file="../../../third_party/polymer/v1_0/components-chromium/paper-fab/paper-fab.html"
              type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_PAPER_HEADER_PANEL_PAPER_HEADER_PANEL_EXTRACTED_JS"
              file="../../../third_party/polymer/v1_0/components-chromium/paper-header-panel/paper-header-panel-extracted.js"
              type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_PAPER_HEADER_PANEL_PAPER_HEADER_PANEL_HTML"
@@ skipping 249 matching lines @@
              file="../../../third_party/polymer/v1_0/components-chromium/polymer/polymer-mini.html"
              type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_POLYMER_POLYMER_HTML"
              file="../../../third_party/polymer/v1_0/components-chromium/polymer/polymer.html"
              type="chrome_html" />
   <structure name="IDR_POLYMER_1_0_WEB_ANIMATIONS_JS_WEB_ANIMATIONS_NEXT_LITE_MIN_JS"
              file="../../../third_party/web-animations-js/sources/web-animations-next-lite.min.js"
              type="chrome_html" />
 </grit-part>