Move isValid/isCurrentColor from Color to StyleColor

Source/core/rendering/EllipsisBox.cpp

Index: Source/core/rendering/EllipsisBox.cpp
diff --git a/Source/core/rendering/EllipsisBox.cpp b/Source/core/rendering/EllipsisBox.cpp
index c5cb7cf373b49b2de4407fce19ae38b17c1c11c1..7dcc2a9f6b0a89e3f5500e7c29f0a9e88ac4eeed 100644
--- a/Source/core/rendering/EllipsisBox.cpp
+++ b/Source/core/rendering/EllipsisBox.cpp
@@ -48,7 +48,7 @@ void EllipsisBox::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset, La
 
         // Select the correct color for painting the text.
         Color foreground = paintInfo.forceBlackText() ? Color::black : renderer()->selectionForegroundColor();
-        if (foreground.isValid() && foreground != styleTextColor)
+        if (foreground != Color::transparent && foreground != styleTextColor)
             context->setFillColor(foreground);
     }
 
@@ -61,7 +61,8 @@ void EllipsisBox::paint(PaintInfo& paintInfo, const LayoutPoint& paintOffset, La
             int shadowX = isHorizontal() ? shadow->x() : shadow->y();
             int shadowY = isHorizontal() ? shadow->y() : -shadow->x();
             FloatSize offset(shadowX, shadowY);
-            drawLooper.addShadow(offset, shadow->blur(), m_renderer->resolveColor(shadow->color()),
+            drawLooper.addShadow(offset, shadow->blur(),
+                m_renderer->resolveColor(shadow->color(), Color::stdShadowColor),
                 DrawLooper::ShadowRespectsTransforms, DrawLooper::ShadowIgnoresAlpha);
         } while ((shadow = shadow->next()));
         drawLooper.addUnmodifiedContent();
@@ -131,7 +132,7 @@ void EllipsisBox::paintSelection(GraphicsContext* context, const LayoutPoint& pa
 {
     Color textColor = m_renderer->resolveColor(style, CSSPropertyColor);
     Color c = m_renderer->selectionBackgroundColor();
-    if (!c.isValid() || !c.alpha())
+    if (!c.alpha())
         return;
 
     // If the text color ends up being the same as the selection background, invert the selection