Cleanup after goog.array, goog.object and goog.isDef removal

CONTRIBUTING.md

@@ -101,20 +101,6 @@ style of the existing OpenLayers 3 code, which includes:
 
  * Do not use assignments inside expressions.
 
- * Avoid the use of `goog.array.clone` with arrays (use slice instead).
-
- * Use `array.length = 0` instead of `goog.array.clear`.
-
- * Use `v !== undefined` instead of `goog.isDef(v)` and `v === null` instead of
-   `goog.isNull(v)`.
-
- * Use ECMAScript 5.1 functions instead of the `goog` equivalents. For example,
-   use `Object.keys(obj)` instead of `goog.object.getKeys(obj)`, `arr.forEach(f)`
-   instead of `goog.array.forEach(arr, f)`, etc ...
-
- * Use bracket notation instead of `goog.object.set` and `goog.object.get` (with
-   two arguments).
-
  * Use uppercase for `@const` variables.
 
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