* Update project.pbxproj files to say Flutter rather than Chromium
Also, the templates now have an empty organization so that we don't cause people to give their apps a Flutter copyright.
* Update the copyright notice checker to require a standard notice on all files
* Update copyrights on Dart files. (This was a mechanical commit.)
* Fix weird license headers on Dart files that deviate from our conventions; relicense Shrine.
Some were already marked "The Flutter Authors", not clear why. Their
dates have been normalized. Some were missing the blank line after the
license. Some were randomly different in trivial ways for no apparent
reason (e.g. missing the trailing period).
* Clean up the copyrights in non-Dart files. (Manual edits.)
Also, make sure templates don't have copyrights.
* Fix some more ORGANIZATIONNAMEs
The average frame time of page transitions on Moto G4 is now very
close to 16ms (the last 10 measurements on our dashboard are
between 15.5ms to 16.7ms and half of them are below 16ms).
It is now much faster than when we disabled it (which was at about
35ms). So I think that we should be able to enable it by default.
I'll leave the flag there until we implement the retained rendering
to bring the frame time comfortably below 16ms.
See https://github.com/flutter/flutter/issues/13736
