Add support for converting Colors to linear RGB; Fix relevant filters

Source/platform/graphics/ColorSpace.h

Index: Source/platform/graphics/ColorSpace.h
diff --git a/Source/platform/graphics/ColorSpace.h b/Source/platform/graphics/ColorSpace.h
index 06918f7ff1f9217d43aca2426ab69fdd4597a244..9b1735a24638ba163f2d14abc68f367690d7059d 100644
--- a/Source/platform/graphics/ColorSpace.h
+++ b/Source/platform/graphics/ColorSpace.h
@@ -27,6 +27,7 @@
 #define ColorSpace_h
 
 #include "platform/PlatformExport.h"
+#include "platform/graphics/Color.h"
 
 namespace WebCore {
 
@@ -36,6 +37,20 @@ enum ColorSpace {
     ColorSpaceLinearRGB
 };
 
+namespace ColorSpaceUtilities {
+
+// Get a pointer to a 8-bit lookup table that will convert color components
+// in the |srcColorSpace| to the |dstColorSpace|.
+// If the conversion cannot be performed, or is a no-op (identity transform),
+// then 0 is returned.
+// (Note that a round-trip - f(B,A)[f(A,B)[x]] - is not lossless in general.)
+const uint8_t* getConversionLUT(ColorSpace dstColorSpace, ColorSpace srcColorSpace = ColorSpaceDeviceRGB);
+
+// Convert a Color assumed to be in the |srcColorSpace| into the |dstColorSpace|.
+Color convertColor(const Color& srcColor, ColorSpace dstColorSpace, ColorSpace srcColorSpace = ColorSpaceDeviceRGB);
+
+} // namespace ColorSpaceUtilities
+
 } // namespace WebCore
 
 #endif // ColorSpace_h