Setup R10/EDX to be valid Oops before stub calls

runtime/vm/intermediate_language_arm64.cc

Index: runtime/vm/intermediate_language_arm64.cc
diff --git a/runtime/vm/intermediate_language_arm64.cc b/runtime/vm/intermediate_language_arm64.cc
index 71bc89ec0b2bccd98b00afb4904bcad401a72218..d6cadf67bd437f0d98f894bbc7410db9c5bcb9a7 100644
--- a/runtime/vm/intermediate_language_arm64.cc
+++ b/runtime/vm/intermediate_language_arm64.cc
@@ -5336,6 +5336,19 @@ void AllocateObjectInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
   __ Drop(ArgumentCount());  // Discard arguments.
 }
 
+
+void DebugStepCheckInstr::EmitNativeCode(FlowGraphCompiler* compiler) {
+  ASSERT(!compiler->is_optimizing());
+  const ExternalLabel label(StubCode::DebugStepCheckEntryPoint());
+  __ LoadImmediate(R4, 0, kNoPP);
+  __ LoadImmediate(R5, 0, kNoPP);
+  compiler->GenerateCall(token_pos(), &label, stub_kind_, locs());
+#if defined(DEBUG)
+  __ LoadImmediate(R4, kInvalidObjectPointer, kNoPP);
+  __ LoadImmediate(R5, kInvalidObjectPointer, kNoPP);
+#endif
+}
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM64