[adapters] 增加小游戏适配部分源码

adapters/platforms/wechat/res/game.js

@@ -0,0 +1,20 @@
+require('adapter-js-path');
+__globalAdapter.init();
+require('cocos2d-js-path');
+require('physics-js-path');
+__globalAdapter.adaptEngine();
+require('./ccRequire');
+
+require('./src/settings');
+// Introduce Cocos Service here
+require('./main');  // TODO: move to common
+
+// Adjust devicePixelRatio
+cc.view._maxPixelRatio = 4;
+
+if (cc.sys.platform !== cc.sys.WECHAT_GAME_SUB) {
+    // Release Image objects after uploaded gl texture
+    cc.macro.CLEANUP_IMAGE_CACHE = true;
+}
+
+window.boot();