Add tests for DataView.prototype.getInt16

...totype/getInt16/byteoffset-is-different-integer-throws.js

...aView/prototype/getInt16/byteoffset-is-negative-throws.js

...type/getInt16/detached-buffer-after-integer-byteoffset.js

.../getInt16/detached-buffer-before-outofrange-byteoffset.js

.../built-ins/DataView/prototype/getInt16/detached-buffer.js

...-ins/DataView/prototype/getInt16/index-is-out-of-range.js

...getInt16/return-abrupt-from-tonumber-byteoffset-symbol.js

...totype/getInt16/return-abrupt-from-tonumber-byteoffset.js

...View/prototype/getInt16/return-value-clean-arraybuffer.js

...ew/prototype/getInt16/return-values-coerced-byteoffset.js

...ataView/prototype/getInt16/return-values-custom-offset.js

test/built-ins/DataView/prototype/getInt16/return-values.js

...aView/prototype/getInt16/this-has-no-dataview-internal.js

...ilt-ins/DataView/prototype/getInt16/this-is-not-object.js

...ns/DataView/prototype/getInt16/to-boolean-littleendian.js