Remove TEXT_MIMETYPES whitelist again.
Remove TEXT_MIMETYPES whitelist again.

Review URL: http://codereview.appspot.com/4641078/

gavioto/rietveld,gavioto/rietveld,nbodepallictr/touchites-test,google-code-export/rietveld,kscharding/integral-solutions-smxq,nareshboddepalli/touchites-test,robfig/rietveld,nareshboddepalli/touchites-test,nareshboddepalli/touchites-test,rietveld-codereview/rietveld,rietveld-codereview/rietveld,arg0/rietveld,salomon1184/rietveld,berkus/rietveld,draem0507/rietveld,google-code-export/rietveld,supriyantomaftuh/rietveld,openlabs/cr.openlabs.co.in,nbodepallictr/touchites-test,openlabs/cr.openlabs.co.in,rietveld-codereview/rietveld,nbodepallictr/touchites-codereview,nareshboddepalli/touchites-codereview,nbodepallictr/touchites-test,Koulio/rietveld,fuzan/rietveld,sajingeo/rietveld,ericmckean/rietveld,robfig/rietveld,google-code-export/rietveld,dushmis/rietveld,aungzanbaw/rietveld,aungzanbaw/rietveld,xtypebee/rietveld,draem0507/rietveld,Koulio/rietveld,berkus/rietveld,kscharding/integral-solutions-smxq,robfig/rietveld,andyzsf/rietveld,v3ss0n/rietveld,dushmis/rietveld,xtypebee/rietveld,fuzan/rietveld,nbodepallictr/touchites-codereview,v3ss0n/rietveld,rietveld-codereview/rietveld,andyzsf/rietveld,foolonhill/rietveld,arg0/rietveld,andyzsf/rietveld,nbodepallictr/touchites-codereview,nareshboddepalli/touchites-codereview,v3ss0n/rietveld,ericmckean/rietveld,gco/rietveld,berkus/rietveld,openlabs/cr.openlabs.co.in,DeanHere/rietveld,gavioto/rietveld,fuzan/rietveld,aungzanbaw/rietveld,gco/rietveld,arg0/rietveld,kscharding/integral-solutions-smxq,xtypebee/rietveld,salomon1184/rietveld,foolonhill/rietveld,salomon1184/rietveld,Koulio/rietveld,foolonhill/rietveld,supriyantomaftuh/rietveld,sajingeo/rietveld,gco/rietveld,draem0507/rietveld,nareshboddepalli/touchites-codereview,sajingeo/rietveld,supriyantomaftuh/rietveld,ericmckean/rietveld,DeanHere/rietveld,DeanHere/rietveld,dushmis/rietveld