Remove some unnecessary static_casts
Remove some unnecessary static_casts

`float = float / static_cast<float>(size_t)` should be equivalent to `float = float / size_t`, implicit conversion does the same thing.

`float = float / double` is not quite equivalent to `float = float / static_cast<float>(double)`. In the former case, the first operand is converted to a double and divided before the result is converted to float.

PiperOrigin-RevId: 437007538

google/ink-stroke-modeler,google/ink-stroke-modeler