[debugger] infrastructure for side-effect-free debug-evaluate.

src/debug/debug-evaluate.h

Index: src/debug/debug-evaluate.h
diff --git a/src/debug/debug-evaluate.h b/src/debug/debug-evaluate.h
index 6b0f48a15d8ac7efe74dda76daaeb0cc44d6a456..e4eee76a3353ef02f0c6fdecce89a42263612aef 100644
--- a/src/debug/debug-evaluate.h
+++ b/src/debug/debug-evaluate.h
@@ -24,6 +24,8 @@ class DebugEvaluate : public AllStatic {
                                    int inlined_jsframe_index,
                                    Handle<String> source);
 
+  static bool IsReadOnly(Handle<BytecodeArray> bytecode_array);
+
  private:
   // This class builds a context chain for evaluation of expressions
   // in debugger.