Cleanup (minor optimization)

src/org/jetbrains/java/decompiler/main/collectors/BytecodeMappingTracer.java

@@ -1,5 +1,5 @@
 /*
- * Copyright 2000-2015 JetBrains s.r.o.
+ * Copyright 2000-2016 JetBrains s.r.o.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -21,6 +21,8 @@ import java.util.*;
 import java.util.Map.Entry;
 
 public class BytecodeMappingTracer {
+  public static final BytecodeMappingTracer DUMMY = new BytecodeMappingTracer();
+
   private int currentSourceLine;
   private StructLineNumberTableAttribute lineNumberTable = null;
   private final Map<Integer, Integer> mapping = new HashMap<Integer, Integer>();  // bytecode offset, source line
@@ -116,4 +118,4 @@ public class BytecodeMappingTracer {
     }
     return res;
   }
-}
+}