DBC: Remove special case from CheckClassInstr. Cleanup.

runtime/vm/flow_graph_compiler_dbc.cc

Index: runtime/vm/flow_graph_compiler_dbc.cc
diff --git a/runtime/vm/flow_graph_compiler_dbc.cc b/runtime/vm/flow_graph_compiler_dbc.cc
index 81c639e89bf50623bd53c0d2fa4d2c8b838ba533..004079ee40382118c42650a294f461f4b80d26c9 100644
--- a/runtime/vm/flow_graph_compiler_dbc.cc
+++ b/runtime/vm/flow_graph_compiler_dbc.cc
@@ -398,6 +398,16 @@ void FlowGraphCompiler::CompileGraph() {
 }
 
 
+uint16_t FlowGraphCompiler::ToEmbeddableCid(intptr_t cid,
+                                            Instruction* instruction) {
+  if (!Utils::IsUint(16, cid)) {
+    instruction->Unsupported();
+    UNREACHABLE();
+  }
+  return static_cast<uint16_t>(cid);
+}
+
+
 #undef __
 #define __ compiler_->assembler()->
 
@@ -417,6 +427,7 @@ void ParallelMoveResolver::EmitMove(int index) {
     __ LoadConstant(destination.reg(), source.constant());
   } else {
     compiler_->Bailout("Unsupported move");
+    UNREACHABLE();
   }
 
   move->Eliminate();