Migrates error suppression from regexps to analysis options.
* Ignore TODOs.
* Ignore strong mode field and method overrides (see `InvalidFieldOverride` and `InvalidMethodOverride` in `strong/info.dart`.
* Remove stale regexp to capture refs to dead `dart:ui_internals` URI.
* Remove stale regexp to capture dead strong mode "will need runtime check to cast to type" error (https://github.com/dart-lang/sdk/issues/24542).
5 regexp downs, another small handful (~4) to go! :)
Also:
- add operator==/hashCode/toString to ViewportDimensions
- add toString to BindingBase
- add toString and debugFillDescription to ScrollBehavior
- fix a bug in the RawGestureDetectorState's replaceGestureRecognizers
- rename MixedViewport's onExtentsUpdate to onExtentChanged
- replace ExtentsUpdateCallback with ValueChanged<double>
- remove a microtask for dispatching scroll start, since it
did not appear to have any purpose
- added dartdocs to Instrumentation until I understood it
- made all event dispatch in Instrumentation drain microtasks
There's no reason to make clients supply a PointerRounter and a
GestureArena when constructing gesture recognizers. These objects are
statics and the gesture recognizers can just grab them directly.
Also, remove the callback constructor arguments. Almost no code used
them. Instead, people seem to prefer using the `..` operator to set
callbacks on the recognizers. Removing the arguments removes a bunch of
boilerplate.
Now we just have one TextSpan class that handles both simple strings, trees of
children, and styling both. This approach simplifies the interface for most
clients.
This patch also removes StyledText, which was weakly typed and tricky to use
correctly. The replacement is RichText, which is strongly typed and uses
TextSpan.
This enables us to exclude `library_names` pending a new stable SDK push (see notes: https://github.com/flutter/flutter/pull/1996). Also excluded are a few lints who's feedback was just getting regexp'ed out. Moving forward, this will allow us to selectively enable specific lints of interest as well.
This makes ScrollBehavior agnostic about the kind of scroll.
This also means ExtentScrollBehavior's comment about being linear is
more relevant (previously it was true of all scroll behaviours).
