Fix testserver to return a correct MIME-type header.
Fix testserver to return a correct MIME-type header.

Originally, testserver was sending "Content-type: text/html" header regardless
of a file extension, due to a bug in TestPageHandler.GetMIMETypeFromName.

Patch by Yuta Kitamura <yutak@google.com>.
Original code review: <http://codereview.chromium.org/100357>

Review URL: http://codereview.chromium.org/115058

git-svn-id: http://src.chromium.org/svn/trunk/src@15510 4ff67af0-8c30-449e-8e8b-ad334ec8d88c

Former-commit-id: 03974ef64ae2977b5cc9b4e4b347bac90a25f85d
meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser,meego-tablet-ux/meego-app-browser