refactor: remove internal usages of deprecated apis (#12316)

Removes a handful of internal usages of APIs that have been deprecated.

Author: crisbeto

src/cdk-experimental/drag-drop/drag.ts

@@ -23,7 +23,7 @@ import {
   ContentChildren,
   QueryList,
 } from '@angular/core';
-import {DOCUMENT} from '@angular/platform-browser';
+import {DOCUMENT} from '@angular/common';
 import {Directionality} from '@angular/cdk/bidi';
 import {CdkDragHandle} from './drag-handle';
 import {CdkDropContainer, CDK_DROP_CONTAINER} from './drop-container';

src/lib/datepicker/datepicker.ts

@@ -442,7 +442,7 @@ export class MatDatepicker<D> implements OnDestroy, CanColor {
   /** Create the popup PositionStrategy. */
   private _createPopupPositionStrategy(): PositionStrategy {
     return this._overlay.position()
-      .flexibleConnectedTo(this._datepickerInput.getPopupConnectionElementRef())
+      .flexibleConnectedTo(this._datepickerInput.getConnectedOverlayOrigin())
       .withTransformOriginOn('.mat-datepicker-content')
       .withFlexibleDimensions(false)
       .withViewportMargin(8)

src/lib/list/selection-list.spec.ts

@@ -455,7 +455,7 @@ describe('MatSelectionList without forms', () => {
     }));
 
     it('should set its initial selected state in the selectedOptions', () => {
-      let optionEl = listItemEl.injector.get(MatListOption);
+      let optionEl = listItemEl.injector.get<MatListOption>(MatListOption);
       let selectedOptions = selectionList.componentInstance.selectedOptions;
       expect(selectedOptions.isSelected(optionEl)).toBeTruthy();
     });
@@ -633,7 +633,8 @@ describe('MatSelectionList without forms', () => {
       // property of the selection list has been updated, the ripple directive can be used.
       // Inspecting the host classes of the options doesn't work because those update as part
       // of the parent template (of the selection-list).
-      const listOptionRipple = listOption[2].query(By.directive(MatRipple)).injector.get(MatRipple);
+      const listOptionRipple = listOption[2].query(By.directive(MatRipple))
+          .injector.get<MatRipple>(MatRipple);
 
       expect(listOptionRipple.disabled)
         .toBe(true, 'Expected ripples of list option to be disabled');