Do not waste space for the fast-case elements backing storage for ...

Do not waste space for the fast-case elements backing storage for 
object-literals with few elements but large element indices.

We can decide at parse time whether the created object literal should
have fast-case of slow-case elements.

Remove unused runtime function.

Committed: http://code.google.com/p/v8/source/detail?r=4100

[Søren Thygesen Gjesse, 2010-03-11 08:28:59]

LGTM

http://codereview.chromium.org/805004/diff/1/5
File src/runtime.cc (right):

http://codereview.chromium.org/805004/diff/1/5#newcode392
src/runtime.cc:392: CONVERT_SMI_CHECKED(fast_elements, args[3]);
Why is this argument not a Boolean object? To save relocinfo space?