I used the wrong identifiers here.

See https://github.com/flutter/flutter/pull/6861

This silences all but two of the warnings from https://travis-ci.org/flutter/flutter/builds/176055550

One of the silenced warnings was a genuine code error.

Some of the others were correct but there was no way for the analyzer to know, and I worked around them.

The remainder are problems with the analyzer, specifically https://github.com/dart-lang/sdk/issues/27827 and https://github.com/dart-lang/sdk/issues/27504.

If a recognizer is interrupted by an exception from a callback, it could be
left in an inconsistent state and be unable to process future events

Also, add some missing docs to http.dart and widgets.dart.

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.

This allows us to adjust exactly which gestures we're listening for
during layout, which I'll use to kill a SizeObserver.

Instead of PointerInputEvent having a "type" field, we now have a
different class for each pointer type.

This has ripple effects throughout the system.

I also did code cleanup in affected files while I was there.

Don't use a timeout to cancel tap tracking. Track only one primary pointer
and ignore non-primary pointers. Update tests to reflect desired behaviors.

Fixes #1779, #1780, #1781.

Now that you import a top-level file for each layer of the Flutter
framework, within the framework we can use relative paths without being
worried about the copy/pasta problem we used to have.

 * Rename GestureTapListener (and friends) To GestureTapCallback to match the
   other gesture callbacks.
 * Replace "ensureFoo" pattern with ??= operator.

This patch is part of a sequence of patches towards fewer top-level libraries.
In this patch, the gesture libraries are combined into one gestures.dart
library.

These files really belong on other libraries.

These gestures use the new gesture detection system.