WIP [esnext] implement async iteration proposal

src/code-stub-assembler.h

Index: src/code-stub-assembler.h
diff --git a/src/code-stub-assembler.h b/src/code-stub-assembler.h
index a5a70c10f80908257ab09e2cf29326a24ea5873e..7359ec51bbc1b981de95abb946ef5e9c903a2ebd 100644
--- a/src/code-stub-assembler.h
+++ b/src/code-stub-assembler.h
@@ -1137,6 +1137,31 @@ class V8_EXPORT_PRIVATE CodeStubAssembler : public compiler::CodeAssembler {
   // Debug helpers
   Node* IsDebugActive();
 
+  // Useful tools for PrintF-style debugging CSA builtins.
+  void ReleasePrint(const char* c_str) {
+    std::string std_str(c_str);
+    std_str += '\n';
+    Handle<String> str =
+        factory()->NewStringFromAsciiChecked(std_str.c_str(), TENURED);
+    CallRuntime(Runtime::kGlobalPrint, NoContextConstant(), HeapConstant(str));
+  }
+
+  void ReleaseDebugPrint(Node* object) {
+    CallRuntime(Runtime::kDebugPrint, NoContextConstant(), object);
+  }
+
+  void Print(const char* c_str) {
+#ifdef DEBUG
+    ReleasePrint(c_str);
+#endif
+  }
+
+  void DebugPrint(Node* object) {
+#ifdef DEBUG
+    ReleaseDebugPrint(object);
+#endif
+  }
+
   // TypedArray/ArrayBuffer helpers
   Node* IsDetachedBuffer(Node* buffer);