Migrate lit-element and lit-html to new lit package

Internal usage of lit-element causes deprecation warnings for downstream
users. This migrates uses to the new "lit" package.

Author: bsidhom

demos/card.html

@@ -48,7 +48,7 @@
   <script type="module">
     import {style as cardStyle} from '../node_modules/@material/mwc-card/mwc-card-css.js';
     import {style as typographyStyle} from '../node_modules/@material/mwc-typography/mwc-typography-css.js';
-    import {LitElement, html} from '../node_modules/lit-element/lit-element.js';
+    import {LitElement, html} from '../node_modules/lit/index.js';
     import '../node_modules/@material/mwc-button/mwc-button.js';
     import '../node_modules/@material/mwc-icon/mwc-icon.js';
     import '../node_modules/@material/mwc-icon-toggle/mwc-icon-toggle.js';

demos/elevation-overlay/index.js

@@ -15,8 +15,8 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 import {style as elevationStyle} from '@material/mwc-elevation-overlay/mwc-elevation-overlay-css';
-import {LitElement, css, html} from 'lit-element';
-import {styleMap} from 'lit-html/directives/style-map';
+import {LitElement, css, html} from 'lit';
+import {styleMap} from 'lit/directives/style-map.js';
 
 import '../shared/demo-header';
 

demos/index.js

@@ -14,7 +14,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
-import {LitElement, html, css} from 'lit-element/lit-element.js';
+import {LitElement, html, css} from 'lit';
 import '@material/mwc-list';
 import '@material/mwc-list/mwc-list-item';
 

demos/shared/demo-header.js

@@ -14,7 +14,7 @@ WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
 */
-import {LitElement, html, css} from 'lit-element/lit-element.js';
+import {LitElement, html, css} from 'lit';
 import '@material/mwc-top-app-bar-fixed';
 import '@material/mwc-icon-button';
 import '@material/mwc-button';

packages/base/aria-property.ts

@@ -35,7 +35,7 @@ function tsDecorator(
       (prototype.constructor as unknown as ReactiveElementInternals);
   if (!descriptor) {
     /**
-     * lit-element uses internal properties with two leading underscores to
+     * lit uses internal properties with two leading underscores to
      * provide storage for accessors
      */
     const litInternalPropertyKey = `__${name}`;

packages/radio/mwc-radio-base.ts

@@ -165,7 +165,7 @@ export class RadioBase extends FormElement {
     super.connectedCallback();
     // Note that we must defer creating the selection controller until the
     // element has connected, because selection controllers are keyed by the
-    // radio's shadow root. For example, if we're stamping in a lit-html map
+    // radio's shadow root. For example, if we're stamping in a lit map
     // or repeat, then we'll be constructed before we're added to a root node.
     //
     // Also note if we aren't using native shadow DOM, we still need a

packages/snackbar/accessible-snackbar-label-directive.ts

@@ -95,7 +95,7 @@ class AccessibleSnackbarLabel extends AsyncDirective {
     // all browsers and screen readers:
     //
     //   1. `textContent = ''` is required for IE11 + JAWS
-    //   2. the lit-html render of `' '` is required for Chrome + JAWS and
+    //   2. the lit render of `' '` is required for Chrome + JAWS and
     //       NVDA
     //
     // All other browser/screen reader combinations support both methods.

scripts/publish-demos.sh

@@ -30,7 +30,7 @@ cat <<-EOF >gh-pages/package.json
   "name": "demos",
   "private": true,
   "dependencies": {
-    "lit-element": "^2.0.0",
+    "lit": "^2.0.0",
     "@webcomponents/webcomponentsjs": "^2.0.0"
   }
 }
@@ -79,4 +79,4 @@ fi
 # # Blow away interim
 # # rm -rf build/default
 # # mv build/interim/build/default build/default
-# # rm -rf build/interim
+# # rm -rf build/interim

scripts/sass-to-lit-css/template.tmpl

@@ -3,5 +3,5 @@
  * Copyright 2021 Google LLC
  * SPDX-LIcense-Identifier: Apache-2.0
  */
-import {css} from 'lit-element';
+import {css} from 'lit';
 export const styles = css`<% content %>`;

test/src/benchmark/button/test-basic.ts

@@ -15,9 +15,9 @@ See the License for the specific language governing permissions and
 limitations under the License.
 */
 import '@material/mwc-button';
-import {html} from 'lit-html';
+import {html} from 'lit';
 import {measureFixtureCreation} from '../../util/helpers';
 
 measureFixtureCreation(html`
   <mwc-button label="Normal"></mwc-button>
-`);
+`);