Reland 7917:

Reland 7917:

Better support for 'polymorphic' JS and external arrays

Allow  keyed store/load stubs to switch between external array and fast JS arrays without forcing a state transition to the generic stub.

There CL consists of two pieces of functionality. First, code stubs for fast element arrays don't immediately transition to the MEGAMORPHIC state when there's a map mismatch. Second, two ICs are cached per map for fast elements, the MONOMORPHIC version, and a new MEGAMORPHIC version that handles two or more different maps and dispatches to shared stubs to perform the array operation.

Committed: http://code.google.com/p/v8/source/detail?r=7935

[danno, 2011-05-17 19:42:02]

Please take a look at the differences between patch set 1 and 2 they, are the
delta changes required to get patch to not cause assertions on build bots.

[Mads Ager (chromium), 2011-05-18 05:15:50]

LGTM