Support string add in crankshaft:

src/ia32/lithium-ia32.cc

Index: src/ia32/lithium-ia32.cc
diff --git a/src/ia32/lithium-ia32.cc b/src/ia32/lithium-ia32.cc
index 9ccd18979e6b8b1e788606f12e25b43a17755e4c..b06928098bd02a33d22016b66cc380f9669035b6 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -2002,6 +2002,13 @@ LInstruction* LChunkBuilder::DoStoreNamedGeneric(HStoreNamedGeneric* instr) {
 }
 
 
+LInstruction* LChunkBuilder::DoStringAdd(HStringAdd* instr) {
+  LOperand* left = UseOrConstant(instr->left());

[fschneider, 2011/04/14 10:26:47]

This should be UseOrConstantAtStart. Otherwise we can't allocate a register if
available since all are blocked because of the call.

[Vitaly Repeshko, 2011/04/14 21:07:18]

Done.

+  LOperand* right = UseOrConstant(instr->right());
+  return MarkAsCall(DefineFixed(new LStringAdd(left, right), eax), instr);
+}
+
+
 LInstruction* LChunkBuilder::DoStringCharCodeAt(HStringCharCodeAt* instr) {
   LOperand* string = UseRegister(instr->string());
   LOperand* index = UseRegisterOrConstant(instr->index());