Remove the additional top padding from CupertinoPageScaffold's MediaQuery when the navigation bar is opaque (as the padding was already consumed by the navigation bar).

Related Issue: #29136

Avoids an implicit downcast + crash in MouseTracker, since the last
pointer event can be a Move or Down event, in addition to Hover.

The UserAccountsDrawerHeader had a bug with the arrow rotating whenever setState was called on its parent. This change makes sure that we check that the state actually changed before allowing the animation to trigger.

Fixes #25801

* Adding linking between higher and lower level classes in the API Docs. ref:#22859

* Fixed links between classes.

This PR limits the framework generated semantic node IDs to be smaller than 2^16, this allows to safely generate semantic node in the engine with IDs >= 2^16 avoiding ID collision (which is done in flutter/engine#8250).

We can remove the hack because https://github.com/flutter/engine/pull/8183
has been rolled into the framework.

* Composite physical layers even if elevation is 0

[Material] Create a FloatingActionButton ThemeData and honor it within the FloatingActionButton (#28735)

Adds a FloatingActionButtonThemeData so that FABs can be themed at the Theme level and independently. The properties that are now on the theme must be defaulted at the build level, in order to respect any contributing theme properties. Because of this, some tests had to be modified to look at properties after they are built. Also, since default behaviors are now tested in the FAB Theme test, some default tests in the FAB test no longer applied and were removed.

The themable properties are:
-backgroundColor
-foregroundColor
-elevation
-disabledElevation
-highlightElevation
-shape

* some space formattings

* always use blocks in if-else if a block is used

* format spaces in for and while

* allow multiline if conditions

* fix missing space

This reverts commit 803b15e0.

Need this manual roll because of golden changes.

flutter/engine@5088735e5 Clip to clip_rect instead of paint bounds (flutter/engine#8183)
flutter/engine@8818a6c41 Roll src/third_party/skia 2c043c288169..4a522b7e916c (3 commits) (flutter/engine#8201)
flutter/engine@048d70bc0 Support dartdevc, dart2js with shared source files, dartdevc sdk (flutter/engine#8105)
flutter/engine@e0782dec7 Roll src/third_party/skia 576b2a5596bc..2c043c288169 (2 commits) (flutter/engine#8200)

The current documentation for `AnimatedWidgetBaseState.forEachTween` is exhaustive but a little hard to grok. This dartdoc example provides some clarity.

Reland composite physical layers and update tests

Fixes https://github.com/flutter/flutter/issues/21232

Fix Flex class docs by replacing 'vertical space' with 'space on its main axis' so that the language fits both column and row. (#29057)

* No shrinking for BackdropFilter's cull rect

This will be a breaking change. Our old behavior may generate confusions
for a sample app like our added golden test: Skia will shrink the cull
rect (and thus the filtered area) to the text. The new behavior will
fill the BackdropFilter to its parent/ancestor clip. This is more
in align with our clip behaviors (no clip by default).

If this breaks your app, wrap the BackdropFilter with a ClipRect.

[wip] The golden images are not uploaded yet. I'll wait for the initial
round of review to approve the golden test before uploading them.

* Statically define the callback

* Add TODO to remind the hacking code removal

* Nit fix

* Update goldens