[Interpreter] Ensure that implicit return undefined is generated.

src/interpreter/bytecode-array-builder.h

Index: src/interpreter/bytecode-array-builder.h
diff --git a/src/interpreter/bytecode-array-builder.h b/src/interpreter/bytecode-array-builder.h
index d4e1c34e540a2d67a22c19d61c7372c78dbf6cfb..a50c28b0ebe875252ea8ff68e34c0fdf58c1e67f 100644
--- a/src/interpreter/bytecode-array-builder.h
+++ b/src/interpreter/bytecode-array-builder.h
@@ -35,6 +35,9 @@ class BytecodeArrayBuilder {
   void set_locals_count(int number_of_locals);
   int locals_count() const;
 
+  // Returns true if the bytecode has an explicit return at the end.
+  bool HasExplicitReturn();
+
   Register Parameter(int parameter_index);
 
   // Constant loads to accumulator.