[es6] implement optional parameters via desugaring (with scoping)

src/runtime/runtime-debug.cc

 // Copyright 2014 the V8 project authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "src/v8.h"
 
 #include "src/accessors.h"
 #include "src/arguments.h"
 #include "src/compiler.h"
 #include "src/debug.h"
@@ skipping 1321 matching lines @@
           return ScopeTypeModule;
         case SCRIPT_SCOPE:
           DCHECK(context_->IsScriptContext() || context_->IsNativeContext());
           return ScopeTypeScript;
         case WITH_SCOPE:
           DCHECK(context_->IsWithContext());
           return ScopeTypeWith;
         case CATCH_SCOPE:
           DCHECK(context_->IsCatchContext());
           return ScopeTypeCatch;
+        case FUNCTION_BODY_SCOPE:
         case BLOCK_SCOPE:
           DCHECK(!scope_info->HasContext() || context_->IsBlockContext());
           return ScopeTypeBlock;
         case EVAL_SCOPE:
           UNREACHABLE();
       }
     }
     if (context_->IsNativeContext()) {
       DCHECK(context_->global_object()->IsGlobalObject());
       // If we are at the native context and have not yet seen script scope,
@@ skipping 1624 matching lines @@
   return Smi::FromInt(isolate->debug()->is_active());
 }
 
 
 RUNTIME_FUNCTION(Runtime_DebugBreakInOptimizedCode) {
   UNIMPLEMENTED();
   return NULL;
 }
 }
 }  // namespace v8::internal