more extension stuff

src/virtual-webgl.js

@@ -429,6 +429,7 @@
 
   function createGetExtensionWrapper(origFn) {
     return function(name) {
+      name = name.toLowerCase();
       // just like the real context each extension needs a virtual class because each use
       // of the extension might be modified (as in people adding properties to it)
       const existingExt = this._extensions[name];
@@ -460,6 +461,8 @@
         wrapper[key] = value;
       }
 
+      this._extensions[name] = wrapper;
+
       return wrapper;
     };
   }

src/virtual-webgl2.js

@@ -596,6 +596,8 @@
         wrapper[key] = value;
       }
 
+      this._extensions[name] = wrapper;
+
       return wrapper;
     },
     activeTexture(unit) {