* 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
* PageView ballistics overshoot the page on some devices
On some devices, such as Cupertino “Plus”-sized devices, scrolling left on the first page of a PageView will overshoot the first page and land on the second page.
The issue is that applyContentDimensions incorrectly detects a content size change due to a floating point comparison on certain screen sizes (18257.400000000005 vs 18257.4)
To fix this, perform a nearEqual comparison in applyContentDimensions.
* Apply style changes to nearEqual for code review feedback.
* MultiTapGestureRecognizer previously would assert if there was no
competition.
* GestureArenaTeam would always select the first recongizer as the
winner even if a later recognizer actually accepted the pointer
sequence.
* debugPrintStack would fail a type check if maxFrames was non-null.
* FractionalOffset.lerp would throw a null-pointer exception if its
second argument was null.
Also, add a number of tests for previously untested lines of code.
Also, make hasOneLineDescription more discerning.
Also, add a test for hasOneLineDescription.
Also, add a test for GravitySimulation, to test the toString.
