Remove unneeded d.ts files from extensions (#19653)

* Remove unneeded d.ts files from extensions

Moves most extensions to use the lib files for the standard library that typescript provides.

* Remove a few more node.d.ts references

extensions/javascript/package.json

@@ -118,5 +118,8 @@
         "url": "http://json.schemastore.org/jsconfig"
       }
     ]
+  },
+  "devDependencies": {
+    "@types/node": "^7.0.4"
   }
 }