fix(Canvas): dispose race condition

[ShaMan123]

calling static dispose before interactive dispose to prevent race condition as described in #7876
should close #7876 and some other strange bugs.

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   82.92 |    75.35 |   86.25 |   82.63 |                                               
 fabric.js |   82.92 |    75.35 |   86.25 |   82.63 | ...,30456,30530,30541-30606,30729,30828,31064 
-----------|---------|----------|---------|---------|-----------------------------------------------

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   82.97 |    75.38 |   86.25 |   82.68 |                                               
 fabric.js |   82.97 |    75.38 |   86.25 |   82.68 | ...,30456,30530,30541-30606,30729,30828,31064 
-----------|---------|----------|---------|---------|-----------------------------------------------

[github-actions]

Code Coverage Summary

> fabric@5.1.0 coverage:report
> nyc report --reporter=lcov --reporter=text

-----------|---------|----------|---------|---------|-----------------------------------------------
File       | % Stmts | % Branch | % Funcs | % Lines | Uncovered Line #s                             
-----------|---------|----------|---------|---------|-----------------------------------------------
All files  |   82.91 |    75.31 |   86.25 |   82.62 |                                               
 fabric.js |   82.91 |    75.31 |   86.25 |   82.62 | ...,30456,30530,30541-30606,30729,30828,31064 
-----------|---------|----------|---------|---------|-----------------------------------------------

[asturur]

The PR seems fine to me, and seem innocent enough to merge it without digging deeper.
But would be nice to understand where the race condition was and caused by which operation.
Is because only the staticCanvas dispose call for a cancel render?

[asturur]

Is approved, so you can merge whenever. But try to explain

[ShaMan123]

Is because only the staticCanvas dispose call for a cancel render?

Yes. What happened was that Canvas#dispose nullified topContext and there was a small gap of time that rendering could occur before StaticCanvas#dispose terminated requested rendering.