chrome://policy: Respect embedded line breaks in long policy values

This CL makes the chrome://policy page respect embedded line breaks in
long policy values, fixing the appearance of pretty-printed string policy
values.

BUG=175999
TEST=Manual


Review URL: https://chromiumcodereview.appspot.com/12230012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@182293 0039d316-1c4b-4281-b951-d872f2087c98

chrome/browser/resources/policy.css

@@ -122,5 +122,6 @@ tbody:not(.show-overflowed-value) > tr.expanded-value-container {
 }
 
 td.expanded-value {
+  white-space: pre;
   word-wrap: break-word;
 }