Fix Smi::IsValid assert in StringCharCodeAt deferred code.

Fix Smi::IsValid assert in StringCharCodeAt deferred code.

Committed: http://code.google.com/p/v8/source/detail?r=6424

[Mads Ager (chromium), 2011-01-20 15:03:17]

http://codereview.chromium.org/6303013/diff/1/src/ia32/lithium-codegen-ia32.cc
File src/ia32/lithium-codegen-ia32.cc (right):

http://codereview.chromium.org/6303013/diff/1/src/ia32/lithium-codegen-ia32.c...
src/ia32/lithium-codegen-ia32.cc:2758: if (!Smi::IsValid(const_index)) {
We shouldn't generate code at all for this instruction in this case. Can we just
do an unconditional deoptimization and return? Or catch this at a higher level
and never build this graph?

[Mads Ager (chromium), 2011-01-21 07:08:18]

LGTM!