[Interpreter] Add support for calling runtime functions which return a pair.

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 5093326bc8fb4c905535432d55f6e87171021e3c..526e16f77273847abfa795d09d39b8e415007d1a 100644
--- a/src/interpreter/bytecode-array-builder.h
+++ b/src/interpreter/bytecode-array-builder.h
@@ -169,6 +169,14 @@ class BytecodeArrayBuilder final {
   BytecodeArrayBuilder& CallRuntime(Runtime::FunctionId function_id,
                                     Register first_arg, size_t arg_count);
 
+  // Call the runtime function with |function_id| that returns a pair of values.
+  // The first argument should be in |first_arg| and all subsequent arguments
+  // should be in registers <first_arg + 1> to <first_arg + 1 + arg_count>. The
+  // return values will be returned in <first_return> and <first_return + 1>.
+  BytecodeArrayBuilder& CallRuntimePair(Runtime::FunctionId function_id,
+                                        Register first_arg, size_t arg_count,
+                                        Register first_return);
+
   // Call the JS runtime function with |context_index|. The the receiver should
   // be in |receiver| and all subsequent arguments should be in registers
   // <receiver + 1> to <receiver + 1 + arg_count>.