docs(common): minor corrections/improvements for NgClass (angular#12327)

Author: michaelgeorgeattard

modules/@angular/common/src/directives/ng_class.ts

@@ -11,8 +11,6 @@ import {CollectionChangeRecord, Directive, DoCheck, ElementRef, Input, IterableD
 import {isListLikeIterable} from '../facade/collection';
 import {isPresent} from '../facade/lang';
 
-
-
 /**
  * @ngModule CommonModule
  *
@@ -31,11 +29,11 @@ import {isPresent} from '../facade/lang';
  *
  * @description
  *
- * The CSS classes are updated as follow depending on the type of the expression evaluation:
- * - `string` - the CSS classes listed in a string (space delimited) are added,
- * - `Array` - the CSS classes (Array elements) are added,
- * - `Object` - keys are CSS class names that get added when the expression given in the value
- *              evaluates to a truthy value, otherwise class are removed.
+ * The CSS classes are updated as follows, depending on the type of the expression evaluation:
+ * - `string` - the CSS classes listed in the string (space delimited) are added,
+ * - `Array` - the CSS classes declared as Array elements are added,
+ * - `Object` - keys are CSS classes that get added when the expression given in the value
+ *              evaluates to a truthy value, otherwise they are removed.
  *
  * @stable
  */
@@ -50,7 +48,6 @@ export class NgClass implements DoCheck {
       private _iterableDiffers: IterableDiffers, private _keyValueDiffers: KeyValueDiffers,
       private _ngEl: ElementRef, private _renderer: Renderer) {}
 
-
   @Input('class')
   set klass(v: string) {
     this._applyInitialClasses(true);