Examples cleanup

Summary:
**Cleanup Examples code**
I linted code in the  `/examples` folder with ESLint config that ships with `create-react-app` and I found a few warnings.

Changes made:
- Removed unused variables, imports
- Refactored switch statement to a simple if statement
- Removed unnecessary escape in Regex

Please let me know if you want me to squash commits or make changes 😄
Closes facebookarchive#1649

Differential Revision: D7085257

fbshipit-source-id: 3292462da3926377537e840dc45ca206a41a8a1b

examples/draft-0-10-0/convertFromHTML/convert.html

@@ -31,7 +31,6 @@
 
       const {
         CompositeDecorator,
-        ContentBlock,
         ContentState,
         Editor,
         EditorState,

examples/draft-0-10-0/entity/entity.html

@@ -33,7 +33,6 @@
         convertFromRaw,
         convertToRaw,
         CompositeDecorator,
-        ContentState,
         Editor,
         EditorState,
       } = Draft;

examples/draft-0-10-0/link/link.html

@@ -32,7 +32,6 @@
       const {
         convertToRaw,
         CompositeDecorator,
-        ContentState,
         Editor,
         EditorState,
         RichUtils,

examples/draft-0-10-0/media/media.html

@@ -108,7 +108,6 @@
         }
 
         _promptForMedia(type) {
-          const {editorState} = this.state;
           this.setState({
             showURLInput: true,
             urlValue: '',

examples/draft-0-10-0/rich/rich.html

@@ -59,17 +59,16 @@
         }
 
         _mapKeyToEditorCommand(e) {
-          switch (e.keyCode) {
-            case 9: // TAB
-              const newEditorState = RichUtils.onTab(
-                e,
-                this.state.editorState,
-                4, /* maxDepth */
-              );
-              if (newEditorState !== this.state.editorState) {
-                this.onChange(newEditorState);
-              }
-              return;
+          if (e.keyCode === 9 /* TAB */) {
+            const newEditorState = RichUtils.onTab(
+              e,
+              this.state.editorState,
+              4, /* maxDepth */
+            );
+            if (newEditorState !== this.state.editorState) {
+              this.onChange(newEditorState);
+            }
+            return;
           }
           return getDefaultKeyBinding(e);
         }

examples/draft-0-10-0/tweet/tweet.html

@@ -81,8 +81,8 @@
        * Super simple decorators for handles and hashtags, for demonstration
        * purposes only. Don't reuse these regexes.
        */
-      const HANDLE_REGEX = /\@[\w]+/g;
-      const HASHTAG_REGEX = /\#[\w\u0590-\u05ff]+/g;
+      const HANDLE_REGEX = /@[\w]+/g;
+      const HASHTAG_REGEX = /#[\w\u0590-\u05ff]+/g;
 
       function handleStrategy(contentBlock, callback, contentState) {
         findWithRegex(HANDLE_REGEX, contentBlock, callback);