Fix wrong conversion from double to bigint in overriden operators of new bigint.

Fix wrong conversion from double to bigint in overriden operators of new bigint.
Fix ambiguous call to pow on Windows.
Fix big_integer_vm_test to use numbers large enough to actually be bigint.
Re-enable dart2js tests.

R=srdjan@google.com

Committed: https://code.google.com/p/dart/source/detail?r=40122

[regis, 2014-09-10 20:24:55]

regis@google.com changed reviewers:
+ srdjan@google.com

[srdjan, 2014-09-10 21:11:48]

LGTM but could you add a test that, e.g.,  multiplication of bigint with double
returns a double.

[regis, 2014-09-10 22:19:05]

On 2014/09/10 21:11:48, srdjan wrote:
> LGTM but could you add a test that, e.g.,  multiplication of bigint with
double
> returns a double.

Done.

Thanks!

[regis, 2014-09-10 22:27:04]

Committed patchset #4 (id:60001) manually as r40122 (presubmit successful).