Do not emit duplicate deoptimization entries for GotoInstr.

runtime/vm/flow_graph_compiler_arm.cc

Index: runtime/vm/flow_graph_compiler_arm.cc
diff --git a/runtime/vm/flow_graph_compiler_arm.cc b/runtime/vm/flow_graph_compiler_arm.cc
index 6bd40496778f10ac44fa8d5adf779a0f9b5fc3c2..a208790223ff038af5af06dc87e55387239edeab 100644
--- a/runtime/vm/flow_graph_compiler_arm.cc
+++ b/runtime/vm/flow_graph_compiler_arm.cc
@@ -708,12 +708,8 @@ void FlowGraphCompiler::EmitInstructionPrologue(Instruction* instr) {
       AddCurrentDescriptor(PcDescriptors::kDeopt,
                            assert->deopt_id(),
                            assert->token_pos());
-    } else if (instr->IsGuardField()) {
-      GuardFieldInstr* guard = instr->AsGuardField();
-      AddCurrentDescriptor(PcDescriptors::kDeopt,
-                           guard->deopt_id(),
-                           Scanner::kDummyTokenIndex);
-    } else if (instr->CanBeDeoptimizationTarget()) {
+    } else if (instr->IsGuardField() ||
+               instr->CanBecomeDeoptimizationTarget()) {
       AddCurrentDescriptor(PcDescriptors::kDeopt,
                            instr->deopt_id(),
                            Scanner::kDummyTokenIndex);