Remove unused and unnecessary constructor from PlatformFont classes.

ui/gfx/platform_font_mac.mm

Index: ui/gfx/platform_font_mac.mm
===================================================================
--- ui/gfx/platform_font_mac.mm	(revision 132062)
+++ ui/gfx/platform_font_mac.mm	(working copy)
@@ -26,9 +26,6 @@
   CalculateMetrics();
 }
 
-PlatformFontMac::PlatformFontMac(const Font& other) {
-}
-
 PlatformFontMac::PlatformFontMac(NativeFont native_font) {
 }
 
@@ -122,11 +119,6 @@
 }
 
 // static
-PlatformFont* PlatformFont::CreateFromFont(const Font& other) {
-  return new PlatformFontMac(other);
-}
-
-// static
 PlatformFont* PlatformFont::CreateFromNativeFont(NativeFont native_font) {
   return new PlatformFontMac(native_font);
 }