SelfAssignment false positive with casting a float variable to int

[DevCharly]

Description of the problem:

The SelfAssignment checker complains about following:

float width = 123.456f;

width = (int) width;

// value of width is now 123

What version of Error Prone are you using?

2.28.0

[cushon]

Some previous discussion in https://github.com/google/error-prone/issues/2196