This consolidates all of the non-template .gitignore rules into the top level .gitignore, to ignore common things more broadly, with less maintenance needed for the .gitignore files. Does not touch the templates, so that they still produce needed .gitignores as part of flutter create.
* 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 53fea9aebb (#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
This yak shave went as follows:
Fix https://github.com/flutter/flutter/issues/8795 by adding stocks to
the examples README.
Notice the layers entry in that README isn't quite right either.
Update that.
Check the layers/README file is worth pointing at.
Update the layers/README.
Let's run some of the layer tests to see if they still work.
Oops, need to update them to gradle.
Ok let's try running them again.
Oops, sector is broken.
Add a test for sector.
Fix sector. Find you need to add an assert to a const constructor.
Notice we need to turn const asserts on for the analyzer.
Notice the analysis_options files are out of sync with each other and
with the full list of lints.
Turn on the lints that should be on.
Fix the bugs that finds.
* s/sky/flutter/ in Android templates
* update engine.version with a compatible engine version
* replace more SkyActivity references with FlutterActivity
