build: fix some remaining relative imports

Fixes that some remaining imports weren't updated to be relative.

Author: devversion

src/material/datepicker/date-range-selection-strategy.ts

@@ -7,8 +7,7 @@
  */
 
 import {Injectable, InjectionToken, Optional, SkipSelf, FactoryProvider} from '@angular/core';
-// TODO: Change to relative import
-import {DateAdapter} from '@angular/material/core';
+import {DateAdapter} from '../core';
 import {DateRange} from './date-selection-model';
 
 /** Injection token used to customize the date range selection behavior. */

src/material/datepicker/date-selection-model.ts

@@ -7,8 +7,7 @@
  */
 
 import {FactoryProvider, Injectable, Optional, SkipSelf, OnDestroy} from '@angular/core';
-// TODO: Change to relative import
-import {DateAdapter} from '@angular/material/core';
+import {DateAdapter} from '../core';
 import {Observable, Subject} from 'rxjs';
 
 /** A class representing a range of dates. */

src/material/list/list-module.ts

@@ -8,7 +8,7 @@
 
 import {NgModule} from '@angular/core';
 import {MatPseudoCheckboxModule, MatRippleModule, MatCommonModule} from '../core';
-import {MatDividerModule, MatDivider} from '@angular/material/divider';
+import {MatDividerModule, MatDivider} from '../divider';
 import {MatActionList} from './action-list';
 import {MatList, MatListItem} from './list';
 import {MatListOption} from './list-option';