Introduce %_IsMinusZero.

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 632b065168e2f75cb355b0756fef46dd16283e28..2a3225b41d59507134231955cc567bb2c1398db9 100644
--- a/src/ia32/lithium-ia32.cc
+++ b/src/ia32/lithium-ia32.cc
@@ -1768,6 +1768,16 @@ LInstruction* LChunkBuilder::DoCompareHoleAndBranch(
 }
 
 
+LInstruction* LChunkBuilder::DoCompareMinusZeroAndBranch(
+    HCompareMinusZeroAndBranch* instr) {
+  LInstruction* goto_instr = CheckElideControlInstruction(instr);
+  if (goto_instr != NULL) return goto_instr;
+  LOperand* value = UseRegister(instr->value());
+  LOperand* scratch = TempRegister();
+  return new(zone()) LCompareMinusZeroAndBranch(value, scratch);
+}
+
+
 LInstruction* LChunkBuilder::DoIsObjectAndBranch(HIsObjectAndBranch* instr) {
   ASSERT(instr->value()->representation().IsSmiOrTagged());
   LOperand* temp = TempRegister();