Setup R10/EDX to be valid Oops before stub calls

runtime/vm/intermediate_language_arm.cc

Index: runtime/vm/intermediate_language_arm.cc
diff --git a/runtime/vm/intermediate_language_arm.cc b/runtime/vm/intermediate_language_arm.cc
index fd7df1cc726ffbabf7e22ffd40412731cfd3c3ff..51c673a94e654a2090199dccbadb982b127d9603 100644
--- a/runtime/vm/intermediate_language_arm.cc
+++ b/runtime/vm/intermediate_language_arm.cc
@@ -6357,6 +6357,19 @@ 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);
+  __ LoadImmediate(R5, 0);
+  compiler->GenerateCall(token_pos(), &label, stub_kind_, locs());
+#if defined(DEBUG)
+  __ LoadImmediate(R4, kInvalidObjectPointer);
+  __ LoadImmediate(R5, kInvalidObjectPointer);
+#endif
+}
+
 }  // namespace dart
 
 #endif  // defined TARGET_ARCH_ARM