Fix html_inline to work with Python 2.6.
Fix html_inline to work with Python 2.6.

Prior to this, the |flags| parameter of |re.sub| was being used, but
this didn't get added until Python 2.7. Instead, compile all regexes
that require this flag; passing flags to |re.compile| has been
supported much longer.

BUG=none

Review URL: https://codereview.chromium.org/12317096
metasmile/grit-i18n,joisig/grit-i18n,megamanfx/grit-i18n,joisig/grit-i18n,willbittner/grit-i18n,invalidstatement/grit-i18n,metasmile/grit-i18n,sevansahumIlovemuhammad/grit-i18n,korusdipl/grit-i18n,skidzen/grit-i18n,qjw/grit-i18n,qjw/grit-i18n,invalidstatement/grit-i18n,lhopps/grit-i18n,willbittner/grit-i18n,korusdipl/grit-i18n,megamanfx/grit-i18n,sevansahumIlovemuhammad/grit-i18n,skidzen/grit-i18n,CrankWheel/grit-i18n,lhopps/grit-i18n