Reduce running time of nan_parse_test.
Reduce running time of nan_parse_test.

It times out on Dartium.
It was testing all combinations of whitespace around all test strings.
Now it just does it around some representable test strings, and only
test space characters around most strings.

Also add a few more tests.

R=sgjesse@google.com

Review URL: https://codereview.chromium.org//94173002

git-svn-id: c93d8a2297af3b929165606efe145742a534bc71@30749 260f80e4-7a28-3924-810f-c04153c831b5

dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dart-archive/dart-sdk,dartino/dart-sdk,dart-archive/dart-sdk,dart-lang/sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dartino/dart-sdk,dart-lang/sdk,dart-lang/sdk