Encode chrome_html output using utf-8.
Encode chrome_html output using utf-8.

BUG=chromium:136389
TEST=NTP page character 8249 is preserved correctly. grit.py unit passes.
Review URL: https://chromiumcodereview.appspot.com/10689160

imuse2012/grit-i18n,imuse2012/grit-i18n,camny125/grit-i18n,camny125/grit-i18n