[turbofan] Introduce lazy bailout, masked as a call.

src/compiler/x64/instruction-selector-x64.cc

Index: src/compiler/x64/instruction-selector-x64.cc
diff --git a/src/compiler/x64/instruction-selector-x64.cc b/src/compiler/x64/instruction-selector-x64.cc
index b735561a1a1c465cf51143360a1cd1d0cffd796c..c43b1829a599fe644a0beea78238f62f2019c03f 100644
--- a/src/compiler/x64/instruction-selector-x64.cc
+++ b/src/compiler/x64/instruction-selector-x64.cc
@@ -1132,7 +1132,7 @@ void InstructionSelector::VisitCall(Node* node, BasicBlock* handler) {
   }
 
   // Select the appropriate opcode based on the call type.
-  InstructionCode opcode;
+  InstructionCode opcode = kArchNop;
   switch (descriptor->kind()) {
     case CallDescriptor::kCallAddress:
       opcode =
@@ -1145,9 +1145,9 @@ void InstructionSelector::VisitCall(Node* node, BasicBlock* handler) {
     case CallDescriptor::kCallJSFunction:
       opcode = kArchCallJSFunction | MiscField::encode(flags);
       break;
-    default:
-      UNREACHABLE();
-      return;
+    case CallDescriptor::kLazyBailout:
+      opcode = kArchLazyBailout | MiscField::encode(flags);
+      break;
   }
 
   // Emit the call instruction.