Fix mixed tabs and spaces in HTML files

[yvan-sraka]

No description provided.

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[yvan-sraka]

I signed it!

[googlebot]

CLAs look good, thanks!

[lincolnfrog]

It is Google's (and generally accepted) code style policy to never use tabs and always use spaces. If we want to fix mixed tabs and spaces, please change it so that everything is spaces.

[lincolnfrog]

Please use ALL spaces, no tabs.

[yvan-sraka]

@lincolnfrog okay, I changed it!