Do not allocate unnecessary ObjectArrays. When allocating an empty growable array, pass it just a…

Do not allocate unnecessary ObjectArrays. When allocating an empty growable array, pass it a compile time constant empty array instead of allocating a new empty array at runtime, since the factory method will anyway allocate its own object array of length 4.

Committed: https://code.google.com/p/dart/source/detail?r=21490

[srdjan, 2013-04-12 23:02:34]

No emails sent... trying again.

[hausner, 2013-04-15 18:04:09]

LGTM.

[srdjan, 2013-04-15 18:07:04]

Committed patchset #1 manually as r21490 (presubmit successful).