Port TypedArray tests from Khronos suite

[bterlson]

There are a number of tests for typed arrays in the Khronos suite. Some of them are out of date (eg. requiring that DataView called as a function should throw), but most should be applicable to the current ES6 draft.

Typed array tests: https://github.com/KhronosGroup/WebGL/blob/master/sdk/tests/conformance/typedarrays

As usual, if porting is going to be problematic for whatever reason we can get coverage from scratch, but a lot of the Khronos tests are fairly in-depth so I'd like to use them if at all possible.

[leobalter]

I believe I solved the coverage for TypedArrays, finally.