This is a bug that only manifests itself in specific settings, such as when running the following code in non-optimistic mode:

var a = new Uint8ClampedArray(10);
for (var i = 0; i < 10; i++) a[i] = i;

This leads to endless recursion in NativeUint8ClampedArray.java:198. The problem is that the rint(double) method has double return type instead of int. As a side note, it's strange this bug hasn't been detected before, Uint8ClampedArray is probably not used a lot.