Add errors for declarations which conflict with catch parameters.

src/ast/scopes.h

 // Copyright 2012 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.
 
 #ifndef V8_AST_SCOPES_H_
 #define V8_AST_SCOPES_H_
 
 #include "src/ast/ast.h"
 #include "src/base/hashmap.h"
 #include "src/pending-compilation-error-handler.h"
@@ skipping 472 matching lines @@
 
   // Inner scope list.
   ZoneList<Scope*>* inner_scopes() { return &inner_scopes_; }
 
   // The scope immediately surrounding this scope, or NULL.
   Scope* outer_scope() const { return outer_scope_; }
 
   // The ModuleDescriptor for this scope; only for module scopes.
   ModuleDescriptor* module() const { return module_descriptor_; }
 
+  AstRawString* catch_variable_name() const {
+    DCHECK(is_catch_scope());
+    DCHECK(num_var_or_const() == 1);
+    return static_cast<AstRawString*>(variables_.Start()->key);
+  }
+
   // ---------------------------------------------------------------------------
   // Variable allocation.
 
   // Collect stack and context allocated local variables in this scope. Note
   // that the function variable - if present - is not collected and should be
   // handled separately.
   void CollectStackAndContextLocals(ZoneList<Variable*>* stack_locals,
                                     ZoneList<Variable*>* context_locals,
                                     ZoneList<Variable*>* context_globals);
 
@@ skipping 310 matching lines @@
   AstValueFactory* ast_value_factory_;
   Zone* zone_;
 
   PendingCompilationErrorHandler pending_error_handler_;
 };
 
 }  // namespace internal
 }  // namespace v8
 
 #endif  // V8_AST_SCOPES_H_