Cleanup namespace usage in platform/fonts/.

Source/platform/fonts/FixedPitchFontType.h

 // Copyright 2014 The Chromium 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 FixedPitchFontType_h
 #define FixedPitchFontType_h
 
 namespace blink {
 
 enum FixedPitchFontType {
     FixedPitchFont,
     NonFixedPitchFont
 };
 
-}
+} // namespace blink
 
 #endif // FixedPitchFontType_h