* 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
* Add framework-side support for system text scale factor.
* Rolling engine to e3404b81a53ba3180c7623a6f2190ebb28518f30
Additional changes rolled in with engine change:
libtxt: implementation of GetRectsForRange that processes a line at a time - e3404b8
Provide an entropy source to the Dart engine (#4161) - e1aa867
libtxt: search for fallback fonts that can match emoji and CJK characters - 8061df1
Roll skia to e4679fa06a. (#4157) - 267e7a8
Update buildroot to 53fea9aebbcc39c6522731471a1a45960ee0685e (#4160) - 02ea7ae
Revert engine Dart roll. (#4158) - 14aab33
Add support for system text scale factor. (#4124) - b2a7f4b
Include _http into sky_engine libraries for analyzer (#4154) - b930f10
libtxt: Remove postprocess_line and improve tracking of X offsets - 86f95f0
libtxt: remove redundant line_widths (#4152) - 14bf515
Roll dart to ade37f931e90b0fdb8fe16d6bf6f089545da55b6 (#4151) - 6f1264f
