Add ignore-enter-key attribute to clear browsing data dialog

This CL changes the behavior of the dialog that pops up at
chrome://settings/clearBrowserData by setting the ignore-enter-key
attribute. The key is ignored because it results in destructive
action and is very easy to trigger by mistake.

Bug: 1108630
Change-Id: If557df2e741a981da1d983bea4fc87989e65bac7
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2316439
Auto-Submit: Orin Jaworski <orinj@chromium.org>
Reviewed-by: dpapad <dpapad@chromium.org>
Commit-Queue: Orin Jaworski <orinj@chromium.org>
Cr-Commit-Position: refs/heads/master@{#791479}

chrome/browser/resources/settings/clear_browsing_data_dialog/clear_browsing_data_dialog.html

@@ -97,7 +97,7 @@
     </style>
 
     <cr-dialog id="clearBrowsingDataDialog"
-        close-text="$i18n{close}" ignore-popstate has-tabs>
+        close-text="$i18n{close}" ignore-popstate has-tabs ignore-enter-key>
       <div slot="title">
         <div>$i18n{clearBrowsingData}</div>
       </div>