[turbofan] Optimize certain chains of Branch into a Switch.

src/compiler/common-operator.h

Index: src/compiler/common-operator.h
diff --git a/src/compiler/common-operator.h b/src/compiler/common-operator.h
index 55b1c8e590c0e27cad221d94735c2d4c77cfcff2..9f2c5751630dbdcf00aa3926003e04dee36bdb3e 100644
--- a/src/compiler/common-operator.h
+++ b/src/compiler/common-operator.h
@@ -33,9 +33,6 @@ std::ostream& operator<<(std::ostream&, BranchHint);
 BranchHint BranchHintOf(const Operator* const);
 
 
-size_t CaseIndexOf(const Operator* const);
-
-
 class SelectParameters FINAL {
  public:
   explicit SelectParameters(MachineType type,
@@ -176,7 +173,8 @@ class CommonOperatorBuilder FINAL : public ZoneObject {
   const Operator* IfTrue();
   const Operator* IfFalse();
   const Operator* Switch(size_t control_output_count);
-  const Operator* Case(size_t index);
+  const Operator* IfValue(int32_t value);
+  const Operator* IfDefault();
   const Operator* Throw();
   const Operator* Return();