Move isValid/isCurrentColor from Color to StyleColor

Source/core/inspector/InspectorFrontendHost.cpp

Index: Source/core/inspector/InspectorFrontendHost.cpp
diff --git a/Source/core/inspector/InspectorFrontendHost.cpp b/Source/core/inspector/InspectorFrontendHost.cpp
index f914a142788087d924509967fbc975ee6761a0fe..770fbcc3893fabac1bd500180477f80c4e5d973d 100644
--- a/Source/core/inspector/InspectorFrontendHost.cpp
+++ b/Source/core/inspector/InspectorFrontendHost.cpp
@@ -276,13 +276,13 @@ String InspectorFrontendHost::loadResourceSynchronously(const String& url)
 String InspectorFrontendHost::getSelectionBackgroundColor()
 {
     Color color = m_frontendPage->theme()->activeSelectionBackgroundColor();
-    return color.isValid() ? color.serialized() : "";
+    return color != Color::transparent ? color.serialized() : "";
 }
 
 String InspectorFrontendHost::getSelectionForegroundColor()
 {
     Color color = m_frontendPage->theme()->activeSelectionForegroundColor();
-    return color.isValid() ? color.serialized() : "";
+    return color != Color::transparent ? color.serialized() : "";
 }
 
 bool InspectorFrontendHost::supportsFileSystems()