test: fix simple/test-typed-arrays

* It incorrectly uses assert(a, b) instead of assert.equal(a, b), meaning all
  relevant assertions will pass regardless of whether they're supposed to when
  a == true.

* It makes the assumption that elements in typed arrays for numerical types
  spanning more than one byte, like Uint32Array, are stored little-endian first
  on all machines.

* It contains assorted mistakes like assert(Int32Array, typeof v4) (that one
  only passes thanks to point 1).