Add explicit keyword to constructors that take one argument

Source/core/css/CSSGradientValue.h

 /*
  * Copyright (C) 2008 Apple Inc. All rights reserved.
  *
  * 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.
  * 2. Redistributions in binary form must reproduce the above copyright
  *    notice, this list of conditions and the following disclaimer in the
@@ skipping 146 matching lines @@
     }
 
     bool equals(const CSSLinearGradientValue&) const;
 
 private:
     CSSLinearGradientValue(CSSGradientRepeat repeat, CSSGradientType gradientType = CSSLinearGradient)
         : CSSGradientValue(LinearGradientClass, repeat, gradientType)
     {
     }
 
-    CSSLinearGradientValue(const CSSLinearGradientValue& other)
+    explicit CSSLinearGradientValue(const CSSLinearGradientValue& other)
         : CSSGradientValue(other, LinearGradientClass, other.gradientType())
         , m_angle(other.m_angle)
     {
     }
 
     RefPtr<CSSPrimitiveValue> m_angle; // may be null.
 };
 
 class CSSRadialGradientValue : public CSSGradientValue {
 public:
@@ skipping 22 matching lines @@
     PassRefPtr<Gradient> createGradient(RenderObject*, const IntSize&);
 
     bool equals(const CSSRadialGradientValue&) const;
 
 private:
     CSSRadialGradientValue(CSSGradientRepeat repeat, CSSGradientType gradientType = CSSRadialGradient)
         : CSSGradientValue(RadialGradientClass, repeat, gradientType)
     {
     }
 
-    CSSRadialGradientValue(const CSSRadialGradientValue& other)
+    explicit CSSRadialGradientValue(const CSSRadialGradientValue& other)
         : CSSGradientValue(other, RadialGradientClass, other.gradientType())
         , m_firstRadius(other.m_firstRadius)
         , m_secondRadius(other.m_secondRadius)
         , m_shape(other.m_shape)
         , m_sizingBehavior(other.m_sizingBehavior)
         , m_endHorizontalSize(other.m_endHorizontalSize)
         , m_endVerticalSize(other.m_endVerticalSize)
     {
     }
 
 
     // Resolve points/radii to front end values.
     float resolveRadius(CSSPrimitiveValue*, RenderStyle*, RenderStyle* rootStyle, float* widthOrHeight = 0);
 
     // These may be null for non-deprecated gradients.
     RefPtr<CSSPrimitiveValue> m_firstRadius;
     RefPtr<CSSPrimitiveValue> m_secondRadius;
 
     // The below are only used for non-deprecated gradients. Any of them may be null.
     RefPtr<CSSPrimitiveValue> m_shape;
     RefPtr<CSSPrimitiveValue> m_sizingBehavior;
 
     RefPtr<CSSPrimitiveValue> m_endHorizontalSize;
     RefPtr<CSSPrimitiveValue> m_endVerticalSize;
 };
 
 } // namespace WebCore
 
 #endif // CSSGradientValue_h