VM: Set breakpoints on x64 and arm64 without patching code.

runtime/vm/code_patcher.h

Index: runtime/vm/code_patcher.h
diff --git a/runtime/vm/code_patcher.h b/runtime/vm/code_patcher.h
index 4e2435f5e9c10e3e0dc54020900db0fb5ddf16f0..f563426099303e7af325bc9c96fcf02996f6cd30 100644
--- a/runtime/vm/code_patcher.h
+++ b/runtime/vm/code_patcher.h
@@ -90,6 +90,9 @@ class CodePatcher : public AllStatic {
 
   static int32_t GetPoolOffsetAt(uword return_address);
   static void SetPoolOffsetAt(uword return_address, int32_t offset);
+  static void PatchPoolPointerCallAt(uword return_address,
+                                     const Code& code,
+                                     uword new_target);
 };
 
 }  // namespace dart