Revert r154797: "Move isValid/isCurrentColor from Color to StyleColor"

Source/core/inspector/InspectorFrontendHost.cpp

 /*
  * Copyright (C) 2007, 2008 Apple Inc. All rights reserved.
  * Copyright (C) 2008 Matt Lilek <webkit@mattlilek.com>
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  *
  * 1.  Redistributions of source code must retain the above copyright
  *     notice, this list of conditions and the following disclaimer.
@@ skipping 264 matching lines @@
         textEncoding = UTF8Encoding();
         useDetector = true;
     }
     RefPtr<TextResourceDecoder> decoder = TextResourceDecoder::create("text/plain", textEncoding, useDetector);
     return decoder->decode(data.data(), data.size()) + decoder->flush();
 }
 
 String InspectorFrontendHost::getSelectionBackgroundColor()
 {
     Color color = RenderTheme::theme().activeSelectionBackgroundColor();
-    return color != Color::transparent ? color.serialized() : "";
+    return color.isValid() ? color.serialized() : "";
 }
 
 String InspectorFrontendHost::getSelectionForegroundColor()
 {
     Color color = RenderTheme::theme().activeSelectionForegroundColor();
-    return color != Color::transparent ? color.serialized() : "";
+    return color.isValid() ? color.serialized() : "";
 }
 
 bool InspectorFrontendHost::supportsFileSystems()
 {
     return true;
 }
 
 void InspectorFrontendHost::requestFileSystems()
 {
     if (m_client)
@@ skipping 50 matching lines @@
 {
     return false;
 }
 
 String InspectorFrontendHost::hiddenPanels()
 {
     return "";
 }
 
 } // namespace WebCore