* 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
Teach Layer and its implementations, RenderObject and its implementations, and PaintingContext to reuse engine layers. The idea is that a concrete RenderObject creates a Layer and holds on to it as long as it needs it (i.e. when it is composited, and the layer type does not change). In return, each Layer object holds on to an EngineLayer and reports it to the engine via addRetained and oldLayer. This allows the Web engine to reuse DOM elements across frames. Without it, each frame drops all previously rendered HTML and regenerates it from scratch.
Breaking change to extremely rarely used ParentDataWidget.debugDescribeInvalidAncestorChain api changing the return type of the method from String to DiagnosticsNode.
* Upgrade everything except matcher.
* Roll matcher (and test)
* Adjust tests that depend on flutter:test directly to depend on a shim
* Require use of package:test shim and remove other references to package:test
* ensures that only semantics boundaries will be added to owner._nodesNeedingSemantics as expected by compiler.
* no longer throws assert if markNeedsSemanticsUpdate is called on non-semantic-boundary render object with a non-semantic-boundary parent.
* Fixes#13109.
* removes onlyLocalUpdates from markNeedsSemanticsUpdate as its no longer needed.
* refactor to ensureAction + some related doc fixes
* Update docs for markNeedsSemanticsUpdate
* rewording
* rewording
* ensureAction test
* ensureAction test
* ensureAction test
* more tests
* refactor to allways reset node
* tiny fixes
* more test
* doc fixes
* one more test
* review comments
* Ensure that a frame is allways scheduled when a RenderObject marks itself as needing a semantics update
Fixes issue 2 described in https://github.com/flutter/flutter/issues/10971
Previously, an object could call `markNeedsSemanticsUpdate` and its wish would never be granted because no frame was scheduled that would actually update the semantics. This caused an issue during scrolling on Android where at the end of the scroll the `RenderIgnorePointer` would stop blocking the semantics of the scrolled view, call `markNeedsSemanticsUpdate`, but then no frame was scheduled to actually put the semantics of the scrolled view back into the semantics tree. That made the scrolled view unusable for a11y users.
At first I was a bit wary to call `requestVisualUpdate` within `markNeedsSemanticsUpdate` because technically the visual is fine, we only need the frame it schedules to update the semantics. However, it seems like we are using `requestVisualUpdate` for exactly that purpose in other places already where we just need an update to the semantics (e.g. 76a50fe0ca/packages/flutter/lib/src/rendering/object.dart (L2408)).
* add tests
