Fix trace2html conversion broken by last trace-viewer deps roll

TBR=skyostil

Review URL: https://codereview.chromium.org/189843012

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@255922 0039d316-1c4b-4281-b951-d872f2087c98
SVN changes up to revision 255922