Introduce %_IsMinusZero.

src/ia32/lithium-ia32.h

Index: src/ia32/lithium-ia32.h
diff --git a/src/ia32/lithium-ia32.h b/src/ia32/lithium-ia32.h
index 600c40f101386f26a8b3309df896bdb0ca1043bf..b0d031a737e18cba8464ba1a5e4d3127955e2209 100644
--- a/src/ia32/lithium-ia32.h
+++ b/src/ia32/lithium-ia32.h
@@ -74,6 +74,7 @@ class LCodeGen;
   V(ClampTToUint8NoSSE2)                        \
   V(ClassOfTestAndBranch)                       \
   V(ClobberDoubles)                             \
+  V(CompareMinusZeroAndBranch)                  \
   V(CompareNumericAndBranch)                    \
   V(CmpObjectEqAndBranch)                       \
   V(CmpHoleAndBranch)                           \
@@ -900,6 +901,22 @@ class LCmpHoleAndBranch V8_FINAL : public LControlInstruction<1, 0> {
 };
 
 
+class LCompareMinusZeroAndBranch V8_FINAL : public LControlInstruction<1, 1> {
+ public:
+  LCompareMinusZeroAndBranch(LOperand* value, LOperand* temp) {
+    inputs_[0] = value;
+    temps_[0] = temp;
+  }
+
+  LOperand* value() { return inputs_[0]; }
+  LOperand* temp() { return temps_[0]; }
+
+  DECLARE_CONCRETE_INSTRUCTION(CompareMinusZeroAndBranch,
+                               "cmp-minus-zero-and-branch")
+  DECLARE_HYDROGEN_ACCESSOR(CompareMinusZeroAndBranch)
+};
+
+
 class LIsObjectAndBranch V8_FINAL : public LControlInstruction<1, 1> {
  public:
   LIsObjectAndBranch(LOperand* value, LOperand* temp) {