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

src/compiler/operator-properties.cc

Index: src/compiler/operator-properties.cc
diff --git a/src/compiler/operator-properties.cc b/src/compiler/operator-properties.cc
index 81299e34ffe830adce4ffa155cf126e0a962a01f..53bd16c0afbdab90cdf42f61de63a402a2dcbc3d 100644
--- a/src/compiler/operator-properties.cc
+++ b/src/compiler/operator-properties.cc
@@ -100,7 +100,8 @@ bool OperatorProperties::IsBasicBlockBegin(const Operator* op) {
   return opcode == IrOpcode::kStart || opcode == IrOpcode::kEnd ||
          opcode == IrOpcode::kDead || opcode == IrOpcode::kLoop ||
          opcode == IrOpcode::kMerge || opcode == IrOpcode::kIfTrue ||
-         opcode == IrOpcode::kIfFalse;
+         opcode == IrOpcode::kIfFalse || opcode == IrOpcode::kIfValue ||
+         opcode == IrOpcode::kIfDefault;
 }
 
 }  // namespace compiler