[interpreter] Fix and test for printing of bytecodes.

src/interpreter/bytecodes.cc

 // Copyright 2015 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/interpreter/bytecodes.h"
 
 #include "src/frames.h"
 #include "src/interpreter/bytecode-traits.h"
 
 namespace v8 {
@@ skipping 473 matching lines @@
 // static
 std::ostream& Bytecodes::Decode(std::ostream& os, const uint8_t* bytecode_start,
                                 int parameter_count) {
   Vector<char> buf = Vector<char>::New(50);
 
   Bytecode bytecode = Bytecodes::FromByte(bytecode_start[0]);
   int prefix_offset = 0;
   OperandScale operand_scale = OperandScale::kSingle;
   if (IsPrefixScalingBytecode(bytecode)) {
     prefix_offset = 1;
+    operand_scale = Bytecodes::PrefixBytecodeToOperandScale(bytecode);
     bytecode = Bytecodes::FromByte(bytecode_start[1]);
   }
   int bytecode_size = Bytecodes::Size(bytecode, operand_scale);
   for (int i = 0; i < prefix_offset + bytecode_size; i++) {
     SNPrintF(buf, "%02x ", bytecode_start[i]);
     os << buf.start();
   }
   const int kBytecodeColumnSize = 6;
   for (int i = prefix_offset + bytecode_size; i < kBytecodeColumnSize; i++) {
     os << "   ";
@@ skipping 172 matching lines @@
   } else {
     std::ostringstream s;
     s << "r" << index();
     return s.str();
   }
 }
 
 }  // namespace interpreter
 }  // namespace internal
 }  // namespace v8