Fixes https://github.com/flutter/flutter/issues/5711

Removed Pesto logo's triggered animation in order to remove the
observable 'hop' when scrolling. The whole curve is now entirely
scroll dependent. Fixes #5907.

This feature is the implementation of an accessibility feature that changes the
size of text by a constant factor.

Fixes #5873

There are still more to go, but this patch completes the widget section.

These are late-breaking docs needed (mostly) for the iOS back gesture.

This property now applies only to the free space in the flex layout (i.e.,
minimize or maximize the amount of free space). Previously, the flexible
children were always allocated a size of zero when MainAxisSize was min. Now
they're allocated the same size that would be if the MainAxisSize was max.

This name is more consistent with our other names.

Fixes #4714

We use `@protected` in this way in StatelessWidget to avoid developers calling
this function directly.

Fixes #5916

Renames stretch constructor to fill for better consistency with
the rest of the framework.

* Roll to Dart SDK `1.20.0-dev.5.0`.

* bumps to `1.20.0-dev.5.0`.
* updates `analyzer` API use.

* Add explicit types.

Fixes #5835.

Fixes https://github.com/flutter/flutter/issues/5775

Added a widget that gives fine control over the use of steppers.
At any single moment, one step is shown with it own controls and
content.

Previously, flexible children were always required to fill their allocated
space. After this change, they can fit loosely into that space and not fill it.
When that happens, the remaining free space is allocated according to the
maixAxisAlignment.

Fixes #5858

Due to a synchronization issue, a PR was merged with a green build
that was supposed to be rebuilt and to fail. This commit fixes the
issue by renaming the usage of a constant.

* Update tools to use `analyzer` from vended Dart SDK.

* updates `flutter_tools` and `flutter_test` to use the SDK-vended `analyzer` package
* tweaks dependency tracking logic to only record the SDK-vended `analyzer` so as not to crash on spurious conflicts (due to transitive dependencies)

* Review fixes.

Fixes #4713.

Fixes https://github.com/flutter/flutter/issues/5684

* refactor _run to runCmd

* replace requiresProjectRoot getter with call to commandValidator

* replace requiresDevice getter with call to findTargetDevice

* trace command requires a debug connection, not a device

* inline androidOnly getter

* rename command methods to verifyTheRunCmd and runCmd

* move common verification into BuildSubCommand

* rename deviceForCommand to device

* rename methods to verifyThenRunCommand and runCommand

As per our style guide, if you can't explain something, refactor it. I
studied this function for a while and still can't explain it, so...

Fixes #5872

See #4434.

Fixes #3208.