Improve annotator performance
Improve annotator performance

Use better character classes to avoid regex backtracking.
Skip regex evaluation on lines that do not begin with @.

BUG=265755

Review URL: https://chromiumcodereview.appspot.com/21227002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@214326 0039d316-1c4b-4281-b951-d872f2087c98

shishkander/recipes-py,shishkander/recipes-py,luci/recipes-py,luci/recipes-py