[Interpreter] Preserve source positions in peephole optimizer.

src/interpreter/bytecodes.h

Index: src/interpreter/bytecodes.h
diff --git a/src/interpreter/bytecodes.h b/src/interpreter/bytecodes.h
index d67a390d121021173bcfd22c29ac2b4621a96917..c0e08574664ed4b7e4eb1f3e350cab31d68eb153 100644
--- a/src/interpreter/bytecodes.h
+++ b/src/interpreter/bytecodes.h
@@ -565,6 +565,10 @@ class Bytecodes {
   // Returns true if the bytecode is a scaling prefix bytecode.
   static bool IsPrefixScalingBytecode(Bytecode bytecode);
 
+  // Returns true if the bytecode has no effects outside the current
+  // interpreter frame.
+  static bool IsWithoutExternalSideEffects(Bytecode bytecode);
+
   // Returns true if |operand_type| is any type of register operand.
   static bool IsRegisterOperandType(OperandType operand_type);