Unify geometry test printers in a test support target.

Source/platform/geometry/FloatSize.h

Index: Source/platform/geometry/FloatSize.h
diff --git a/Source/platform/geometry/FloatSize.h b/Source/platform/geometry/FloatSize.h
index f4b196a423ea41bd52ca32db8016ef011d4e7405..fdc3d4bb35dcb542fd0da0cf585be6aa679b28b9 100644
--- a/Source/platform/geometry/FloatSize.h
+++ b/Source/platform/geometry/FloatSize.h
@@ -31,6 +31,7 @@
 #include "platform/geometry/IntPoint.h"
 #include "third_party/skia/include/core/SkSize.h"
 #include "wtf/MathExtras.h"
+#include <iosfwd>
 
 #if OS(MACOSX)
 typedef struct CGSize CGSize;
@@ -204,6 +205,10 @@ inline IntPoint flooredIntPoint(const FloatSize& p)
     return IntPoint(clampTo<int>(floorf(p.width())), clampTo<int>(floorf(p.height())));
 }
 
+// Redeclared here to avoid ODR issues.
+// See platform/testing/GeometryPrinters.h.
+void PrintTo(const FloatSize&, std::ostream*);
+
 } // namespace blink
 
 #endif // FloatSize_h