Add fine-grained diff implementation to LiveEdit engine.

test/mjsunit/debug-liveedit-newsource.js

 // Copyright 2010 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 46 matching lines @@
 print("new source: " + new_source);
 
 var change_log = new Array();
 var result = Debug.LiveEdit.SetScriptSource(script, new_source, false, change_log);
 print("Result: " + JSON.stringify(result) + "\n");
 print("Change log: " + JSON.stringify(change_log) + "\n");
 
 assertEquals("Capybara", ChooseAnimal());
 // Global variable do not get changed (without restarting script).
 assertEquals(25, something1);
-// Function is oneliner, so currently it is treated as damaged and not patched.
-assertEquals(17, ChooseNumber());
+// We should support changes in oneliners.
+assertEquals(18, ChooseNumber());
 assertEquals("Hello Peter", ChooseAnimal.Factory()("Peter"));