TBR: Change BaseMatcher to Matcher in pub test file.
TBR: Change BaseMatcher to Matcher in pub test file.

Review URL: https://codereview.chromium.org//19789015

git-svn-id: a962b240025cf0577aa172e20f49ccb159ba6be1@25357 260f80e4-7a28-3924-810f-c04153c831b5

maxwellpeterson-wf/pub,dart-lang/pub,dart-lang/pub,cjkao/dart-pub,computmaxer/pub