Removed static type inference and add a dynamic test for string addition.

Removed static type inference and add a dynamic test for string addition.
The complexity of static type inference never really paid off, and as an 
analysis it didn't fit well with codegen frame propagation.

[Lasse Reichstein, 2009-06-24 09:38:34]

Review, please.

[Erik Corry, 2009-06-24 11:46:34]

LGTM.  Removing code is always good.  After talking to Bill we agreed that we
could remove it because any static typing we need later will be done in a
different way.

http://codereview.chromium.org/146077/diff/1013/17
File src/ia32/codegen-ia32.cc (right):

http://codereview.chromium.org/146077/diff/1013/17#newcode935
Line 935: frame_->InvokeBuiltin(Builtins::STRING_ADD_LEFT, CALL_FUNCTION, 2);
I wonder whether the stub is faster here.  It doesn't have to do the IS_STRING
test in js.

http://codereview.chromium.org/146077/diff/1013/18
File src/ia32/virtual-frame-ia32.cc (right):

http://codereview.chromium.org/146077/diff/1013/18#newcode222
Line 222: // copies or constants so the original was not copied.
Copies of copies?

http://codereview.chromium.org/146077/diff/1013/19
File src/ia32/virtual-frame-ia32.h (right):

http://codereview.chromium.org/146077/diff/1013/19#newcode82
Line 82: }
I'd prefer for these whitespace changes not to be made.

http://codereview.chromium.org/146077/diff/1013/25
File src/x64/virtual-frame-x64.cc (right):

http://codereview.chromium.org/146077/diff/1013/25#newcode435
Line 435: // No need to set the copied flag---there are no copies.
The comment here doesn't match the comment in the IA32 version.  That makes it
hard to diff them.

[Lasse Reichstein, 2009-06-24 12:33:07]

http://codereview.chromium.org/146077/diff/1013/17
File src/ia32/codegen-ia32.cc (right):

http://codereview.chromium.org/146077/diff/1013/17#newcode935
Line 935: frame_->InvokeBuiltin(Builtins::STRING_ADD_LEFT, CALL_FUNCTION, 2);
Good idea.
I'll commit this for now, and make a test afterwards.

http://codereview.chromium.org/146077/diff/1013/18
File src/ia32/virtual-frame-ia32.cc (right):

http://codereview.chromium.org/146077/diff/1013/18#newcode222
Line 222: // copies or constants so the original was not copied.
Bad merge. I'll restore the original.