MouseTracker moved to rendering

Summary

Context

Description of change

Migration guide

Timeline

References

Summary

MouseTracker and related symbols are moved from the
gestures package, resulting in error messages such as
undefined classes or methods. Import them from rendering
package instead.

Context

Prior to this change MouseTracker was part of the
gestures package. This brought troubles when we found out
that code related to MouseTracker often wanted to
import from the rendering package.

Since MouseTracker turned out to be more connected to
rendering than gestures, we have moved it and its
related code to rendering.

Description of change

The file mouse_tracking.dart has been moved from the
gestures package to rendering. All symbols in the said
file have been moved without keeping backward compatibility.

Migration guide