[csa] Add Unreachable() and use it after throw sites

src/compiler/raw-machine-assembler.cc

Index: src/compiler/raw-machine-assembler.cc
diff --git a/src/compiler/raw-machine-assembler.cc b/src/compiler/raw-machine-assembler.cc
index b751e2d5b5232644c90e6a2b2f436e8c40eac9bb..0e101770c3b1022ae1c5a6b3288984bd6a514709 100644
--- a/src/compiler/raw-machine-assembler.cc
+++ b/src/compiler/raw-machine-assembler.cc
@@ -166,6 +166,13 @@ void RawMachineAssembler::PopAndReturn(Node* pop, Node* v1, Node* v2,
 
 void RawMachineAssembler::DebugBreak() { AddNode(machine()->DebugBreak()); }
 
+void RawMachineAssembler::Unreachable() {
+  Node* values[] = {UndefinedConstant()};  // Unused.
+  Node* ret = MakeNode(common()->Throw(), 1, values);
+  schedule()->AddThrow(CurrentBlock(), ret);
+  current_block_ = nullptr;
+}
+
 void RawMachineAssembler::Comment(const char* msg) {
   AddNode(machine()->Comment(msg));
 }