Call changeFile() for ChangeType.ADD
Call changeFile() for ChangeType.ADD

AnalysisDriver.addFile() means: analyze this file when anything about
its dependenciea changes, e.g. it is a part of an open directory. But
generated files are not, we don't want to analyze *them* per se. But
they might affect added files, so we should call changeFile() instead.

Change-Id: I729119b3be077cbc99480ca66698d6b67425c79f
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/215380
Reviewed-by: Brian Wilkerson <1f7641b6b14c52b9163524ab8d9aabff80176f21@google.com>
Reviewed-by: Michal Terepeta <150b8621a675a5d55b9991692bfca28a89cfbab1@google.com>
Commit-Queue: Konstantin Shcheglov <09e4d7516628963212bf4aace2f97603d2b706e4@google.com>

dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk,dart-lang/sdk