[turbofan] Add the RoundInt32ToFloat32 operator to turbofan.

src/compiler/ia32/code-generator-ia32.cc

Index: src/compiler/ia32/code-generator-ia32.cc
diff --git a/src/compiler/ia32/code-generator-ia32.cc b/src/compiler/ia32/code-generator-ia32.cc
index f63bc22e4344fe65a875ea3c7cc341a98caa362a..e11a99c8da8a88da189acf902e4873042c989369 100644
--- a/src/compiler/ia32/code-generator-ia32.cc
+++ b/src/compiler/ia32/code-generator-ia32.cc
@@ -749,6 +749,9 @@ void CodeGenerator::AssembleArchInstruction(Instruction* instr) {
       __ add(i.OutputRegister(), Immediate(0x80000000));
       break;
     }
+    case kSSEInt32ToFloat32:
+      __ cvtsi2ss(i.OutputDoubleRegister(), i.InputOperand(0));
+      break;
     case kSSEInt32ToFloat64:
       __ cvtsi2sd(i.OutputDoubleRegister(), i.InputOperand(0));
       break;