Allow loading SkyX files on Mac desktop

packages/flutter/example/game/BUILD.gn

@@ -21,5 +21,8 @@ sky_app("game") {
       "assets/Icon@2x.png",
       "ios/LaunchScreen.storyboardc",
     ]
+  } else if (is_mac) {
+    info_plist = "mac/Info.plist"
+    xibs = [ "mac/sky_mac.xib" ]
   }
 }

packages/flutter/example/game/mac/Info.plist

+<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+<dict>
+	<key>CFBundleDevelopmentRegion</key>
+	<string>en</string>
+	<key>CFBundleExecutable</key>
+	<string>game_app</string>
+	<key>CFBundleIconFile</key>
+	<string></string>
+	<key>CFBundleIdentifier</key>
+	<string>org.domokit.sky.asteroids</string>
+	<key>CFBundleInfoDictionaryVersion</key>
+	<string>6.0</string>
+	<key>CFBundleName</key>
+	<string>Asteroids</string>
+	<key>CFBundlePackageType</key>
+	<string>APPL</string>
+	<key>CFBundleShortVersionString</key>
+	<string>1.0</string>
+	<key>CFBundleSignature</key>
+	<string>????</string>
+	<key>CFBundleVersion</key>
+	<string>1</string>
+	<key>LSMinimumSystemVersion</key>
+	<string>10.6</string>
+	<key>NSHumanReadableCopyright</key>
+	<string>Copyright © 2015 The Chromium Authors. All rights reserved.</string>
+	<key>NSMainNibFile</key>
+	<string>sky_mac</string>
+	<key>NSPrincipalClass</key>
+	<string>SkyApplication</string>
+</dict>
+</plist>