Remove grab-bag includes of v8.h from several files.

src/ast-numbering.h

 // 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.
 
 #ifndef V8_AST_NUMBERING_H_
 #define V8_AST_NUMBERING_H_
 
 namespace v8 {
 namespace internal {
 
+// Forward declarations.
+class FunctionLiteral;
+class Isolate;
+class Zone;
+
 namespace AstNumbering {
 // Assign type feedback IDs and bailout IDs to an AST node tree.
 //
 bool Renumber(Isolate* isolate, Zone* zone, FunctionLiteral* function);
 }
-}
-}  // namespace v8::internal
+
+}  // namespace internal
+}  // namespace v8
 
 #endif  // V8_AST_NUMBERING_H_