Revert of [debugger] remove debugger statement support from FCG/CS.

test/debugger/debug/debug-set-variable-value.js

 // Copyright 2012 the V8 project authors. All rights reserved.
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 // met:
 //
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-// Flags: --no-always-opt
 
 var Debug = debug.Debug;
 
 // Accepts a function/closure 'fun' that must have a debugger statement inside.
 // A variable 'variable_name' must be initialized before debugger statement
 // and returned after the statement. The test will alter variable value when
 // on debugger statement and check that returned value reflects the change.
 function RunPauseTest(scope_number, expected_old_result, variable_name,
     new_value, expected_new_result, fun) {
   var actual_old_result = fun();
@@ skipping 237 matching lines @@
   assertEquals(12, abc);
   debugger;
   assertEquals(42, abc);
 
   if (exception != null) {
     assertUnreachable("Exception in listener\n" + exception.stack);
   }
 }
 
 Debug.setListener(null);