Centralize TextStream functions to remove RenderTreeAsText dependency of the filters

Source/core/platform/graphics/GraphicsLayer.cpp

Index: Source/core/platform/graphics/GraphicsLayer.cpp
diff --git a/Source/core/platform/graphics/GraphicsLayer.cpp b/Source/core/platform/graphics/GraphicsLayer.cpp
index dd8373088100c4c66c47cef6587a351d6bb47797..238bac84701dbcee9e4744399418c62681725c30 100644
--- a/Source/core/platform/graphics/GraphicsLayer.cpp
+++ b/Source/core/platform/graphics/GraphicsLayer.cpp
@@ -554,12 +554,6 @@ void GraphicsLayer::collectTrackedRepaintRects(Vector<FloatRect>& rects) const
         rects.append(repaintIt->value);
 }
 
-void GraphicsLayer::writeIndent(TextStream& ts, int indent)
-{
-    for (int i = 0; i != indent; ++i)
-        ts << "  ";
-}
-
 void GraphicsLayer::dumpLayer(TextStream& ts, int indent, LayerTreeFlags flags) const
 {
     writeIndent(ts, indent);