Add third_party/html_office to .gitignore.

BUG=333125

Review URL: https://codereview.chromium.org/132023007

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@244060 0039d316-1c4b-4281-b951-d872f2087c98

.gitignore

@@ -218,6 +218,7 @@ v8.log
 /third_party/googlemac
 /third_party/gperf
 /third_party/guava/src
+/third_party/html_office
 /third_party/httpcomponents-client
 /third_party/httpcomponents-core
 /third_party/hunspell