Add infrastructure to optimize line numbers, not enabled yet.

Bug:
Change-Id: I04722643c69a7425998fd427c51501271540c748
diff --git a/src/test/debugTestResources/LineNumberOptimization1.java b/src/test/debugTestResources/LineNumberOptimization1.java
new file mode 100644
index 0000000..c25ecc6
--- /dev/null
+++ b/src/test/debugTestResources/LineNumberOptimization1.java
@@ -0,0 +1,14 @@
+// Copyright (c) 2017, the R8 project authors. Please see the AUTHORS file
+// for details. All rights reserved. Use of this source code is governed by a
+// BSD-style license that can be found in the LICENSE file.
+
+public class LineNumberOptimization1 {
+  private static void callThisFromSameFile() {
+    System.out.println("callThisFromSameFile");
+    LineNumberOptimization2.callThisFromAnotherFile();
+  }
+
+  public static void main(String[] args) {
+    callThisFromSameFile();
+  }
+}