This splits the frame pipeline into two, beginFrame and drawFrame.
As part of making this change I added some debugging hooks that helped
debug the issues that came up:
* I added debugPrintScheduleFrameStacks which prints a stack whenever
a frame is actually scheduled, so you can see why frames are being
scheduled.
* I added some toString output to EditableText and RawKeyboardListener.
* I added a scheduler_tester.dart library for scheduler library tests.
* I changed the test framework to flush microtasks before pumping.
* Some asserts that had the old string literal form were replaced by
asserts with messages.
I also fixed a few subtle bugs that this uncovered:
* setState() now calls `ensureVisualUpdate`, rather than
`scheduleFrame`. This means that calling it from an
AnimationController callback does not actually schedule an extra
redundant frame as it used to.
* I corrected some documentation.
* Manually fix every use of Point.x and Point.y
Some of these were moved to dx/dy, but not all.
* Manually convert uses of the old gradient API
* Remove old reference to Point.
* Mechanical changes
I applied the following at the root of the Flutter repository:
git ls-files -z | xargs -0 sed -i 's/\bPoint[.]origin\b/Offset.zero/g'
git ls-files -z | xargs -0 sed -i 's/\bPoint[.]lerp\b/Offset.lerp/g'
git ls-files -z | xargs -0 sed -i 's/\bnew Point\b/new Offset/g'
git ls-files -z | xargs -0 sed -i 's/\bconst Point\b/const Offset/g'
git ls-files -z | xargs -0 sed -i 's/\bstatic Point /static Offset /g'
git ls-files -z | xargs -0 sed -i 's/\bfinal Point /final Offset /g'
git ls-files -z | xargs -0 sed -i 's/^\( *\)Point /\1Offset /g'
git ls-files -z | xargs -0 sed -i 's/ui[.]Point\b/ui.Offset/g'
git ls-files -z | xargs -0 sed -i 's/(Point\b/(Offset/g'
git ls-files -z | xargs -0 sed -i 's/\([[{,]\) Point\b/\1 Offset/g'
git ls-files -z | xargs -0 sed -i 's/@required Point\b/@required Offset/g'
git ls-files -z | xargs -0 sed -i 's/<Point>/<Offset>/g'
git ls-files -z | xargs -0 sed -i 's/[.]toOffset()//g'
git ls-files -z | xargs -0 sed -i 's/[.]toPoint()//g'
git ls-files -z | xargs -0 sed -i 's/\bshow Point, /show /g'
git ls-files -z | xargs -0 sed -i 's/\bshow Point;/show Offset;/g'
* Mechanical changes - dartdocs
I applied the following at the root of the Flutter repository:
git ls-files -z | xargs -0 sed -i 's/\ba \[Point\]/an [Offset]/g'
git ls-files -z | xargs -0 sed -i 's/\[Point\]/[Offset]/g'
* Further improvements and a test
* Fix minor errors from rebasing...
* Roll engine
* Return null from VM.mainView if no view exists
* Retry in connectToServiceProtocol if a view is not yet available
* Do not explicitly call exit from the benchmarks - it will not cleanly shut down the engine
