docs(core/di/binding.ts): Correct typo

Closes angular#4099

Author: arosenberg01

modules/angular2/src/core/di/binding.ts

@@ -67,7 +67,8 @@ export class Binding {
  *
  * ## Example
  *
- * Because `toAlias` and `toClass` are often confused, the example contains both use cases for easy
+ * Because `toAlias` and `toClass` are often confused, the example contains both use cases for
+ * easy
  * comparison.
  *
  * ```javascript
@@ -364,7 +365,8 @@ export class BindingBuilder {
  *
  * ## Example
  *
- * Becuse `toAlias` and `toClass` are often confused, the example contains both use cases for easy
+ * Because `toAlias` and `toClass` are often confused, the example contains both use cases for
+ * easy
  * comparison.
  *
  * ```javascript