traces from base and the shell view dart isolate simultaneously.
Trace files contain samples from multiple sources and must be merged
separately

Fix tab indicator animation so it doesn't snap to the previous tab.

Add the ability to color filter background images

If you tap multiple tabs in a row, the tab animation used to snap to the
last selected tab when starting a new animation. Fix that.

Also use the BuilderTransition so we don't have to rebuild the tab bar
every frame.

Minedigger pubspec

Stocks pubspec

Fix tests after examples move

Optimize circular clips slightly

This patch avoids creating weak references on every paint call by caching the
Path object between paints.

Get rid of the Direction parameter for animation Forces.

Just infer it from the sign of the velocity. That's what odeon does.

Improves particle performance

Move examples to the root

Fix asserts related to image drawing.

Remove the flicker from MimicOverlay

There were two problems:

1) When starting the mimic, we put up a bad frame because although we set the
   `begin` value of the animation, we were building using the current `value`,
   which hadn't been updated.

2) When stoping the mimic, we'd dirty a component during didUnmount, which
   wouldn't get cleaned until the next frame. Now we're sure to clean all the
   components before leaving flushBuild.

Rev pub packages

Also, teach big_red_button how to make a REVISION file in sky_engine/lib.

Use localToGlobal and globalToLocal in MimicOverlay

Also, make RenderStack support negative positions with clipping so that we can
expand objects that are partially offscreen.

First example pubspec

Fix 505

Widget coordinate transforms: localToGlobal(), globalToLocal()

Specify local build paths when using sky_tool.

directory to support using sky_tool with local
builds.

Add a --checked argument to sky_tool start

The --checked argument runs SkyShell in checked mode, which turns on type
checking and asserts.

Use the new virtual directory flag for sky_server instead of a symlink to prevent infinite subdirectory recursion