Missing docs for properties/methods

#### Bug, feature request, or proposal:
Bug/Proposal.

#### What is the expected behavior?
The listed propeties/methods have no docs.

#### What is the current behavior?
Here's the list that I found of all missing docs.

| Class | Properties | Methods |
| ------------- | ------------- | -------------
| [**MatAutocompleteTrigger**](https://material.angular.io/components/autocomplete/api#MatAutocompleteTrigger) |`autocomplete`, `panelOpen`
| [**MatChip**](https://material.angular.io/components/chips/api#MatChip) | `ariaSelected` |
| [**MatChipInput**](https://material.angular.io/components/chips/api#MatChipInput) | `focused` | `focus`
| [**MatChipList**](https://material.angular.io/components/chips/api#MatChipList) | `controlType` , `ngControl`, `role` | `onContainerClick`, `setDescribedByIds`
| [**MatDialogClose**](https://material.angular.io/components/dialog/api#MatDialogClose) | `dialogRef`
| [**MatDialogRef**](https://material.angular.io/components/dialog/api#MatDialogRef) | `id`
| [**MatDialogTitle**](https://material.angular.io/components/dialog/api#MatDialogTitle) | `id`
| [**MatDatepickerInput**](https://material.angular.io/components/datepicker/api#MatDatepickerInput) | | `registerOnValidatorChange`, `validate`
| [**MatExpansionPanelHeader**](https://material.angular.io/components/expansion/api#MatExpansionPanelHeader) | `panel`
| [**MatError**](https://material.angular.io/components/form-field/api#MatError) | `id`
| [**MatInput**](https://material.angular.io/components/input/api#MatInput) | `empty`, `ngControl`, `shouldLabelFloat` | `focus`, `onContainerClick`, `setDescribedByIds`
| [**MatListOption**](https://material.angular.io/components/list/api#MatListOption) | `selectionList`
| [**MatSelect**](https://material.angular.io/components/select/api#MatSelect) | `ngControl`, `shouldLabelFloat`
| [**MatSlideToggleChange**](https://material.angular.io/components/slide-toggle/api#MatSlideToggleChange) | All `MatSlideToggleChange` properties |
| [**SimpleSnackBar**](https://material.angular.io/components/snack-bar/api#SimpleSnackBar) | `snackBarRef`

#### Is there anything else we should know?
Related to #8789.