Speed up typed array constructors.

Speed up typed array constructors.
 - Avoid calls into ToPositiveInteger for valid cases of 'undefined' arguments.
  (Otherwise it calls into runtime).
 - Reduce the checks performed in case offset for TypedArrayFromArrayBuffer
  constructor is called with no offset argument.

R=yangguo@chromium.org

Committed: https://code.google.com/p/v8/source/detail?r=17567

[Dmitry Lomov (no reviews), 2013-11-06 16:44:12]

PTAL. That's the end of low-hanging fruit in typed array constructors +
preparations to more hydrogenizing.

[Yang, 2013-11-07 10:14:11]

LGTM.

https://codereview.chromium.org/59763010/diff/1/src/typedarray.js
File src/typedarray.js (right):

https://codereview.chromium.org/59763010/diff/1/src/typedarray.js#newcode311
src/typedarray.js:311: 0 : ToPositiveInteger(byteOffset,
'invalid_data_view_offset');
I think we use 4 space indent after linebreak. I see you got 2 space indent
somewhere else too, so I guess it's your choice.

[Dmitry Lomov (no reviews), 2013-11-07 14:56:45]

Committed patchset #1 manually as r17567 (presubmit successful).