Relax the clientWidth constraint in the controls tests

[vincentfretin]

Description:

In #5632, the line was changed from

canvas.clientWidth = 1000;

that really did nothing because canvas.clientWidth is read-only.

to

assert.isAtLeast(canvas.clientWidth, 1000);

but those tests now fail on my Ubuntu machine, the window opens with width 886.

Changes proposed:

• Relax the clientWidth constraint in the controls tests to use 800, from the tests it should be a value above 500

[dmarcos]

Thanks